Sample records for stream flow soil

  1. Using Distributed-Hydrology-Soil-Vegetation Model to Study Road Effects on Stream flow and Soil Moisture

    Cuo, L.; Giambelluca, T. W.; Ziegler, A. D.; Nullet, M. A.


    The distributed-hydrology-soil-vegetation model (DHSVM) was applied in Pang Khum Experimental Watershed (PKEW), located near 19.05\\deg N, 98.65\\deg E in the mountainous region of northern Thailand, headwaters of the Chao Phraya River system. PKEW has a highly seasonal rainfall regime, with 90% of the annual 1200-1400 mm rainfall occurring during the southwest summer monsoon. The elevation of PKEW ranges from approximately 1100 to 1500 m. Total road area including road banks is about 1.2% of the basin area. About 57% of the road area occurs on slopes steeper than 10%. All roads are unpaved. Land cover in PKEW is affected by swidden agriculture. Six land cover and nine soil classes are identified in the basin. We have been working in the area since 1997 as part of the Thailand Roads Project (TRP). Within the basin, we are monitoring microclimate at two sites, soil moisture at four sites, and rainfall at five sites. Streamflow is measured at the outlet. Based on digital elevation data, DHSVM explicitly accounts for the spatial distribution of the stream and road networks, soil depth, soil and vegetation types. The model run period, including warm up, calibration and validation, is from August 1997 to January 2001. Field measurements provide forcing data, calibration data, and guidance in parameter selection. Model calibration and validation were done by aggregating simulated hourly soil moisture and stream flow into daily values and comparing them with aggregated daily measurements. For the calibration period, RMSEs of soil moisture and streamflow were lower than the observed variability as represented by the standard deviation, median absolute deviation, and (for stream flow) interquartile range. Model performance drops in validation period, but RMSEs remain near or lower than observed variability. We ran DHSVM with and without roads to examine their effects. Significant effects of roads were found despite the very low proportion of the watershed covered by roads

  2. The effect of reforestation on stream flow in Upper Nan river basin using Soil and Water Assessment Tool (SWAT model

    Winai Wangpimool


    The simulation was performed using three reforestation scenarios to assess stream flow:(1 improved disturbed forest, (2 field crops and range grass, and (3 both disturbed forest and field crops. The results of reforestation from scenarios 1 and 3 can increase stream flow in the drought season and can also reduce the flow in the wet season in the main stream and its tributaries. For scenario 2 Reforestation had no significant effect on the main stream.

  3. [Estimation of topographical factors in revised universal soil loss model based on maximum up-stream flow path].

    Luo, Hong; Ma, You-xin; Liu, Wen-jun; Li, Hong-mei


    By using maximum upstream flow path, a self-developed new method for calculating slope length value based on Arc Macro Language (AML), five groups of DEM data for different regions in Bijie Prefecture of Guizhou Province were extracted to compute the slope length and topographical factors in the Prefecture. The time cost for calculating the slope length and the values of the topographical factors were analyzed, and compared with those by iterative slope length method based on AML (ISLA) and on C++ (ISLC). The results showed that the new method was feasible to calculate the slope length and topographical factors in revised universal soil loss model, and had the same effect as iterative slope length method. Comparing with ISLA, the new method had a high computing efficiency and greatly decreased the time consumption, and could be applied to a large area to estimate the slope length and topographical factors based on AML. Comparing with ISLC, the new method had the similar computing efficiency, but its coding was easily to be written, modified, and debugged by using AML. Therefore, the new method could be more broadly used by GIS users.


    Yuan-Fan TSAI; Huai-Kuang TSAI; Cheng-Yan KAO


    The Chi-Chi earthquake in 1999 caused disastrous landslides, which triggered numerous debris flows and killed hundreds of people. A critical rainfall intensity line for each debris-flow stream is studied to prevent such a disaster. However, setting rainfall lines from incomplete data is difficult, so this study considered eight critical factors to group streams, such that streams within a cluster have similar rainfall lines. A genetic algorithm is applied to group 377 debris-flow streams selected from the center of an area affected by the Chi-Chi earthquake. These streams are grouped into seven clusters with different characteristics. The results reveal that the proposed method effectively groups debris-flow streams.

  5. WATSTORE Stream Flow Basin Characteristics File

    U.S. Geological Survey, Department of the Interior — The Stream Flow Basin Characteristics file contains information about the drainage basins of selected USGS gaging stations. Data elements of this file were converted...

  6. Derivation of soil-specific streaming potential electrical parameters from hydrodynamic characteristics of partially saturated soils

    Jougnot, Damien; Revil, A; Doussan, Claude; 10.2136/vzj2011.0086


    Water movement in unsaturated soils gives rise to measurable electrical potential differences that are related to the flow direction and volumetric fluxes, as well as to the soil properties themselves. Laboratory and field data suggest that these so-called streaming potentials may be several orders of magnitudes larger than theoretical predictions that only consider the influence of the relative permeability and electrical conductivity on the self potential (SP) data. Recent work has partly improved predictions by considering how the volumetric excess charge in the pore space scales with the inverse of water saturation. We present a new theoretical approach that uses the flux-averaged excess charge, not the volumetric excess charge, to predict streaming potentials. We present relationships for how this effective excess charge varies with water saturation for typical soil properties using either the water retention or the relative permeability function. We find large differences between soil types and the pred...

  7. Estimating overland flow erosion capacity using unit stream power

    Hui-Ming SHIH; Chih Ted YANG


    Soil erosion caused by water flow is a complex problem.Both empirical and physically based approaches were used for the estimation of surface erosion rates.Their applications are mainly limited to experimental areas or laboratory studies.The maximum sediment concentration overland flow can carry is not considered in most of the existing surface erosion models.The lack of erosion capacity limitation may cause over estimations of sediment concentration.A correlation analysis is used in this study to determine significant factors that impact surface erosion capacity.The result shows that the unit stream power is the most dominant factor for overland flow erosion which is consistent with experimental data.A bounded regression formula is used to reflect the limits that sediment concentration cannot be less than zero nor greater than a maximum value.The coefficients used in the model are calibrated using published laboratory data.The computed results agree with laboratory data very well.A one dimensional overland flow diffusive wave model is used in conjunction with the developed soil erosion equation to simulate field experimental results.This study concludes that the non-linear regression method using unit stream power as the dominant factor performs well for estimating overland flow erosion capacity.

  8. Low-flow characteristics of Virginia streams

    Austin, Samuel H.; Krstolic, Jennifer L.; Wiegand, Ute


    Low-flow annual non-exceedance probabilities (ANEP), called probability-percent chance (P-percent chance) flow estimates, regional regression equations, and transfer methods are provided describing the low-flow characteristics of Virginia streams. Statistical methods are used to evaluate streamflow data. Analysis of Virginia streamflow data collected from 1895 through 2007 is summarized. Methods are provided for estimating low-flow characteristics of gaged and ungaged streams. The 1-, 4-, 7-, and 30-day average streamgaging station low-flow characteristics for 290 long-term, continuous-record, streamgaging stations are determined, adjusted for instances of zero flow using a conditional probability adjustment method, and presented for non-exceedance probabilities of 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, 0.02, 0.01, and 0.005. Stream basin characteristics computed using spatial data and a geographic information system are used as explanatory variables in regional regression equations to estimate annual non-exceedance probabilities at gaged and ungaged sites and are summarized for 290 long-term, continuous-record streamgaging stations, 136 short-term, continuous-record streamgaging stations, and 613 partial-record streamgaging stations. Regional regression equations for six physiographic regions use basin characteristics to estimate 1-, 4-, 7-, and 30-day average low-flow annual non-exceedance probabilities at gaged and ungaged sites. Weighted low-flow values that combine computed streamgaging station low-flow characteristics and annual non-exceedance probabilities from regional regression equations provide improved low-flow estimates. Regression equations developed using the Maintenance of Variance with Extension (MOVE.1) method describe the line of organic correlation (LOC) with an appropriate index site for low-flow characteristics at 136 short-term, continuous-record streamgaging stations and 613 partial-record streamgaging stations. Monthly

  9. Modeling soil detachment capacity by rill flow using hydraulic parameters

    Wang, Dongdong; Wang, Zhanli; Shen, Nan; Chen, Hao


    The relationship between soil detachment capacity (Dc) by rill flow and hydraulic parameters (e.g., flow velocity, shear stress, unit stream power, stream power, and unit energy) at low flow rates is investigated to establish an accurate experimental model. Experiments are conducted using a 4 × 0.1 m rill hydraulic flume with a constant artificial roughness on the flume bed. The flow rates range from 0.22 × 10-3 m2 s-1 to 0.67 × 10-3 m2 s-1, and the slope gradients vary from 15.8% to 38.4%. Regression analysis indicates that the Dc by rill flow can be predicted using the linear equations of flow velocity, stream power, unit stream power, and unit energy. Dc by rill flow that is fitted to shear stress can be predicted with a power function equation. Predictions based on flow velocity, unit energy, and stream power are powerful, but those based on shear stress, especially on unit stream power, are relatively poor. The prediction based on flow velocity provides the best estimates of Dc by rill flow because of the simplicity and availability of its measurements. Owing to error in measuring flow velocity at low flow rates, the predictive abilities of Dc by rill flow using all hydraulic parameters are relatively lower in this study compared with the results of previous research. The measuring accuracy of experiments for flow velocity should be improved in future research.

  10. Source Water Flow Pathways In Forested, Mountain, Headwater Streams: A Link Between Sediment Movement Patterns And Stream Water Chemistry.

    Martin, S.; Conklin, M. H.; Liu, F.


    Three years of continuous and discrete sediment and water quality data, from four forested, mountain, headwater catchments in the Sierra Nevada, is used to identify water sources, determine the importance of sub-surface flow pathways, detect any changes in source waters due to seasonal variation or drought, and link flow pathways with observed patterns of in-channel sediment movement within the study watersheds. Patterns in stream chemistry and turbidity point to infiltration as the dominant flow pathway within these catchments. Data support a flow pathway conceptual model in which precipitation water infiltrates into the shallow or deeper subsurface, increasing the hydraulic head of the water table and pushing pre-event water into the stream ahead of event water. Study catchments contain perennial streams and are characterized by a Mediterranean climate with a distinct wet and dry season. Sites are located in the rain-snow transition zone with snow making up 40 to 60 percent of average annual precipitation. Barring human disturbances such as logging/grazing (compaction) or fire (hydrophobicity), catchment soils have high infiltration capacities. Springs and seeps maintain baseflow during the summer low-flow season, and shifting chemical signals within the streams indicate the increased importance of sub-surface water sources during drought years. End-member mixing analysis was conducted to identify possible water end members. Turbidity hysteresis patterns described by previous studies show in-channel sources are dominant for discharge events year round, and there is no difference in fine sediment delivery to streams with or without a soil protecting layer of snow on the land surface. The dominance of sub-surface water sources and evidence for infiltration flow fits with turbidity data, as little material is reaching the stream due to erosive overland flow. An understanding of flow pathways provides a foundation for sustainable land use management in forested

  11. Wave-Flow Interactions and Acoustic Streaming

    Chafin, Clifford E


    The interaction of waves and flows is a challenging topic where a complete resolution has been frustrated by the essential nonlinear features in the hydrodynamic case. Even in the case of EM waves in flowing media, the results are subtle. For a simple shear flow of constant n fluid, incident radiation is shown to be reflected and refracted in an analogous manner to Snell's law. However, the beam intensities differ and the system has an asymmetry in that an internal reflection gap opens at steep incident angles nearly oriented with the shear. For EM waves these effects are generally negligible in real systems but they introduce the topic at a reduced level of complexity of the more interesting acoustic case. Acoustic streaming is suggested, both from theory and experimental data, to be associated with vorticity generation at the driver itself. Bounds on the vorticity in bulk and nonlinear effects demonstrate that the bulk sources, even with attenuation, cannot drive such a strong flow. A review of the velocity...

  12. Laboratory investigation on streaming potential for sandy soil and weathered rock; Shitsunai jikken ni yoru sashitsu jiban oyobi fuka ganban no ryudo den`i no kento

    Sato, H.; Shima, H. [OYO Corp., Tokyo (Japan)


    Laboratory experiment on sandy soil and weathered rock was conducted to clarify the generation mechanism of streaming potential due to underground fluid. Streaming potential is caused by underground fluid flow, namely by fluid flow in porous substances as electrokinetic phenomenon. In experiment, Inagi sand, Toyoura sand and strongly decomposed weathered granite were used. In Inagi and Toyoura sands, positive streaming potential was observed downstream in fluid flow. Streaming potential could be nearly determined as primary function of fluid velocity, and generated streaming potential increased with fluid resistivity. Streaming potential was higher in Inagi sand than Toyoura sand, probably depending on hydraulic radius, size of bleeding channel, and conductivity of sand surface. In weathered granite, negative streaming potential was measured. In the case of positive {zeta} potential, negative streaming potential is theoretically generated downstream in fluid flow. This experiment suggested possible generation of negative streaming potential in some kinds of ground. 2 refs., 6 figs., 1 tab.

  13. Modulated stagnation-point flow and steady streaming

    Merchant, Gregory J.; Davis, Stephen H.


    Plane stagnation-point flow is modulated in the free stream so that the velocity components are proportional to K(H) + K cos omega t. Similarity solutions of the Navier-Stokes equations are examined using high-frequency asymptotics for K and K(H) of unit order. Special attention is focused on the steady streaming generated in this flow with strongly non-parallel streamlines.

  14. Ensemble stream flow predictions using the ECMWF forecasts

    Kiczko, Adam; Romanowicz, Renata; Osuch, Marzena; Pappenberger, Florian; Karamuz, Emilia


    Floods and low flows in rivers are seasonal phenomena that can cause several problems to society. To anticipate high and low flow events, flow forecasts are crucial. They are of particular importance in mountainous catchments, where the lead time of forecasts is usually short. In order to prolong the forecast lead-time, numerical weather predictions (NWPs) are used as a hydrological model driving force. The forecasted flow is commonly given as one value, even though it is uncertain. There is an increasing interest in accounting for the uncertainty in flood early warning and decision support systems. When NWP are given in the form of ensembles, such as the ECMWF forecasts, the uncertainty of these forecasts can be accounted for. Apart from the forecast uncertainty the uncertainty related to the hydrological model used also plays an important role in the uncertainty of the final flow prediction. The aim of this study is the development of a stream flow prediction system for the Biała Tarnowska, a mountainous catchment in the south of Poland. We apply two different hydrological models. One is a conceptual HBV model for rainfall-flow predictions, applied within a Generalised Likelihood Uncertainty Estimation (GLUE) framework, the second is a data-based DBM model, adjusted for Polish conditions by adding the Soil Moisture Accounting (SMA) and snow-melt modules. Both models provide the uncertainty of the predictions, but the DBM approach is much more numerically efficient, therefore more suitable for the real-time forecasting.. The ECMWF forecasts require bias reduction in order to correspond to observations. Therefore we applied Quantile Mapping with and without seasonal adjustment for bias correction. Up to seven-days ahead forecast skills are compared using the Relative Operation Characteristic (ROC) graphs, for the flood warning and flood alarm flow value thresholds. The ECMWF forecasts are obtained from the project TIGGE (http

  15. Simulation of dust streaming in toroidal traps: Stationary flows

    Reichstein, Torben; Piel, Alexander [IEAP, Christian-Albrechts-Universitaet, D-24098 Kiel (Germany)


    Molecular-dynamic simulations were performed to study dust motion in a toroidal trap under the influence of the ion drag force driven by a Hall motion of the ions in E x B direction, gravity, inter-particle forces, and friction with the neutral gas. This article is focused on the inhomogeneous stationary streaming motion. Depending on the strength of friction, the spontaneous formation of a stationary shock or a spatial bifurcation into a fast flow and a slow vortex flow is observed. In the quiescent streaming region, the particle flow features a shell structure which undergoes a structural phase transition along the flow direction.

  16. Impacts of Climate Change on Stream Flow in the Upper Mississippi River Basin: A Regional Climate Model Perspective, The

    Manoj Jha; Zaitao Pan; Takle, Eugene S.; Roy Gu


    We evaluate the impact of climate change on stream flow in the Upper Mississippi River Basin (UMRB) by using a regional climate model (RCM) coupled with a hydrologic model, the Soil and Water Assessment Tool (SWAT). The SWAT model was calibrated and validated against measured stream flow data using observed weather data and inputs from the Environmental Protection Agency's BASINS (Better Assessment Science Integrating Point and Nonpoint Sources) geographical information/database system. The c...


    Serdar GÖNCÜ


    Full Text Available Determining low-flows and their periodicities is very important for sustainably using and managing streams which are one of the most important water resources. In this study, EPA’s DFLOW software has been used for the analysis of the main stream and tributaries of the Porsuk watershed. Flow data sets from selected stream flow gauge stations located in the Porsuk Watershed have been provided by the General Directorate of State Hydraulic Works. Hydrologically and biologically based low-flow criteria like 7Q10, 4B3 have been calculated by using the DFLOW software and how these stream tributaries have been affected over the last 45 years has been determined. Also temporal trends of low-flow periods and 7-day average low flows whose return period is a year (7Q1 have been examined. As a result of this study, increasing trends have been determined on some tributaries used for irrigation purposes and after reservoir construction. Undisturbed tributaries have decreasing low-flow patterns. Increases in temperature and precipitation changes due to climate change should be consideredwith more care. In addition, in the planning and use of water control structures, such as hydroelectrical power plant dams, such studies are important for the more efficient use and sustainabilityof the limited surface water resources in our country.

  18. Particle migration and sorting in microbubble streaming flows

    Thameem, Raqeeb; Hilgenfeldt, Sascha


    Ultrasonic driving of semicylindrical microbubbles generates strong streaming flows that are robust over a wide range of driving frequencies. We show that in microchannels, these streaming flow patterns can be combined with Poiseuille flows to achieve two distinctive, highly tunable methods for size-sensitive sorting and trapping of particles much smaller than the bubble itself. This method allows higher throughput than typical passive sorting techniques, since it does not require the inclusion of device features on the order of the particle size. We propose a simple mechanism, based on channel and flow geometry, which reliably describes and predicts the sorting behavior observed in experiment. It is also shown that an asymptotic theory that incorporates the device geometry and superimposed channel flow accurately models key flow features such as peak speeds and particle trajectories, provided it is appropriately modified to account for 3D effects caused by the axial confinement of the bubble. PMID:26958103

  19. Hot-wire amperometric monitoring of flowing streams.

    Wang, J; Jasinski, M; Flechsig, G U; Grundler, P; Tian, B


    This paper describes the design of a hot-wire electrochemical flow detector, and the advantages accrued from the effects of locally increased temperature, mainly thermally induced convection, upon the amperometric monitoring of flowing streams. A new hydrodynamic modulation voltammetric approach is presented, in which the solution flow rate remains constant while the temperature of the working electrode is modulated. Factors influencing the response, including the flow rate, temperature pulse, or applied potential, have been investigated. The hot-wire operation results also in a significant enhancement of the flow injection amperometric response. The minimal flow rate dependence observed with the heated electrode should benefit the on-line monitoring of streams with fluctuated natural convection, as well as various in-situ remote sensing applications.

  20. Particle migration and sorting in microbubble streaming flows.

    Thameem, Raqeeb; Rallabandi, Bhargav; Hilgenfeldt, Sascha


    Ultrasonic driving of semicylindrical microbubbles generates strong streaming flows that are robust over a wide range of driving frequencies. We show that in microchannels, these streaming flow patterns can be combined with Poiseuille flows to achieve two distinctive, highly tunable methods for size-sensitive sorting and trapping of particles much smaller than the bubble itself. This method allows higher throughput than typical passive sorting techniques, since it does not require the inclusion of device features on the order of the particle size. We propose a simple mechanism, based on channel and flow geometry, which reliably describes and predicts the sorting behavior observed in experiment. It is also shown that an asymptotic theory that incorporates the device geometry and superimposed channel flow accurately models key flow features such as peak speeds and particle trajectories, provided it is appropriately modified to account for 3D effects caused by the axial confinement of the bubble.

  1. Transport and transformation of soil-derived CO2, CH4 and DOC sustain CO2 supersaturation in small boreal streams.

    Rasilo, Terhi; Hutchins, Ryan H S; Ruiz-González, Clara; Del Giorgio, Paul A


    Streams are typically supersaturated in carbon dioxide (CO2) and methane (CH4), and are recognized as important components of regional carbon (C) emissions in northern landscapes. Whereas there is consensus that in most of the systems the CO2 emitted by streams represents C fixed in the terrestrial ecosystem, the pathways delivering this C to streams are still not well understood. We assessed the contribution of direct soil CO2 injection versus the oxidation of soil-derived dissolved organic C (DOC) and CH4 in supporting CO2 supersaturation in boreal streams in Québec. We measured the concentrations of CO2, CH4 and DOC in 43 streams and adjacent soil waters during summer base-flow period. A mass balance approach revealed that all three pathways are significant, and that the mineralization of soil-derived DOC and CH4 accounted for most of the estimated stream CO2 emissions (average 75% and 10%, respectively), and that these estimated contributions did not change significantly between the studied low order (≤3) streams. Whereas some of these transformations take place in the channel proper, our results suggest that they mainly occur in the hyporheic zones of the streams. Our results further show that stream CH4 emissions can be fully explained by soil CH4 inputs. This study confirms that these boreal streams, and in particular their hyporheic zones, are extremely active processors of soil derived DOC and CH4, not just vents for soil produced CO2.

  2. Methods for estimating flow-duration and annual mean-flow statistics for ungaged streams in Oklahoma

    Esralew, Rachel A.; Smith, S. Jerrod


    -basin characteristics by using a k-means cluster analysis. Three regions were identified for Oklahoma on the basis of the clustering of gaging stations and a manual delineation of distinguishable hydrologic and geologic boundaries: Region 1 (western Oklahoma excluding the Oklahoma and Texas Panhandles), Region 2 (north- and south-central Oklahoma), and Region 3 (eastern and central Oklahoma). A total of 228 regression equations (225 flow-duration regressions and three annual mean-flow regressions) were developed using ordinary least-squares and left-censored (Tobit) multiple-regression techniques. These equations can be used to estimate 75 flow-duration statistics and annual mean-flow for ungaged streams in the three regions. Drainage-basin characteristics that were statistically significant independent variables in the regression analyses were (1) contributing drainage area; (2) station elevation; (3) mean drainage-basin elevation; (4) channel slope; (5) percentage of forested canopy; (6) mean drainage-basin hillslope; (7) soil permeability; and (8) mean annual, seasonal, and monthly precipitation. The accuracy of flow-duration regression equations generally decreased from high-flow exceedance (low-exceedance probability) to low-flow exceedance (high-exceedance probability) . This decrease may have happened because a greater uncertainty exists for low-flow estimates and low-flow is largely affected by localized geology that was not quantified by the drainage-basin characteristics selected. The standard errors of estimate of regression equations for Region 1 (western Oklahoma) were substantially larger than those standard errors for other regions, especially for low-flow exceedances. These errors may be a result of greater variability in low flow because of increased irrigation activities in this region. Regression equations may not be reliable for sites where the drainage-basin characteristics are outside the range of values of independent vari

  3. Ptaquiloside from bracken in stream water at base flow and during storm events.

    Clauson-Kaas, Frederik; Ramwell, Carmel; Hansen, Hans Chr B; Strobel, Bjarne W


    The bracken fern (Pteridium spp.) densely populates both open and woodland vegetation types around the globe. Bracken is toxic to livestock when consumed, and a group of potent illudane-type carcinogens have been identified, of which the compound ptaquiloside (PTA) is the most abundant. The highly water soluble PTA has been shown to be leachable from bracken fronds, and present in the soil and water below bracken stands. This has raised concerns over whether the compound might pose a risk to drinking water sources. We investigated PTA concentrations in a small stream draining a bracken-infested catchment at base flow and in response to storm events during a growth season, and included sampling of the bracken canopy throughfall. Streams in other bracken-dominated areas were also sampled at base flow for comparison, and a controlled pulse experiment was conducted in the field to study the in-stream dynamics of PTA. Ptaquiloside concentrations in the stream never exceeded 61 ng L(-1) in the base flow samples, but peaked at 2.2 μg L(-1) during the studied storm events. The mass of PTA in the stream, per storm event, was 7.5-93 mg from this catchment. A clear temporal connection was observed between rainfall and PTA concentration in the stream, with a reproducible time lag of approx. 1 h from onset of rain to elevated concentrations, and returning rather quickly (about 2 h) to base flow concentration levels. The concentration of PTA behaved similar to an inert tracer (Cl(-)) in the pulse experiment over a relative short time scale (minutes-hours) reflecting no PTA sorption, and dispersion and dilution considerably lowered the observed PTA concentrations downstream. Bracken throughfall revealed a potent and lasting source of PTA during rainfall, with concentrations up to 169 μg L(-1), that did not decrease over the course of the event. In the stream, the throughfall contribution to PTA cannot be separated from a possible below-ground input from litter, rhizomes

  4. In-stream flow needs of the Athabasca River

    Van Meer, T. [Syncrude Canada Ltd., Edmonton, AB (Canada)


    This presentation described the importance of the in-stream flow needs of the Athabasca River. Physical and biological river functions are affected by the amount of water in the stream. The functional needs of the river are met by maintaining minimum flows. Since the development of oil sands requires large volumes of water, there has been a general perception of low river flows in the Lower Athabasca River. Syncrude Canada Ltd. challenges this perception with defensible information. The Surface Water Working Group of the Cumulative Environmental Management Association (CEMA) has created a sub-group called the In-Stream Flow Needs (IFN) to establish environmental criteria and develop management systems to protect the in-stream flow needs of the lower Athabasca River. The objective is to launch a science-based program that identifies the habitat suitability for key fish species as a function of the physical hydraulics of the river. Another objective is to have a science-based objective for flow management in place by the end of 2005. The tasks of the IFN include radio telemetry, on-ice data collection, hydraulic surveys, and modeling. tabs., figs.

  5. Ptaquiloside from bracken in stream water at base flow and during storm events

    Clauson-Kaas, Frederik; Ramwell, Carmel; Hansen, Hans Chr. Bruun


    water soluble PTA has been shown to be leachable from bracken fronds, and present in the soil and water below bracken stands. This has raised concerns over whether the compound might pose a risk to drinking water sources. We investigated PTA concentrations in a small stream draining a bracken......-infested catchment at base flow and in response to storm events during a growth season, and included sampling of the bracken canopy throughfall. Streams in other bracken-dominated areas were also sampled at base flow for comparison, and a controlled pulse experiment was conducted in the field to study the in......-stream dynamics of PTA. Ptaquiloside concentrations in the stream never exceeded 61 ng L(-1) in the base flow samples, but peaked at 2.2 μg L(-1) during the studied storm events. The mass of PTA in the stream, per storm event, was 7.5-93 mg from this catchment. A clear temporal connection was observed between...

  6. Soil disturbance as a driver of increased stream salinity in a semiarid watershed undergoing energy development

    Bern, Carleton R.; Clark, Melanie L.; Schmidt, Travis S.; Holloway, JoAnn M.; Mcdougal, Robert


    Salinization is a global threat to the quality of streams and rivers, but it can have many causes. Oil and gas development were investigated as one of several potential causes of changes in the salinity of Muddy Creek, which drains 2470 km2 of mostly public land in Wyoming, U.S.A. Stream discharge and salinity vary with seasonal snowmelt and define a primary salinity-discharge relationship. Salinity, measured by specific conductance, increased substantially in 2009 and was 53-71% higher at low discharge and 33-34% higher at high discharge for the years 2009-2012 compared to 2005-2008. Short-term processes (e.g., flushing of efflorescent salts) cause within-year deviations from the primary relation but do not obscure the overall increase in salinity. Dissolved elements associated with increased salinity include calcium, magnesium, and sulfate, a composition that points to native soil salts derived from marine shales as a likely source. Potential causes of the salinity increase were evaluated for consistency by using measured patterns in stream chemistry, slope of the salinity-discharge relationship, and inter-annual timing of the salinity increase. Potential causes that were inconsistent with one or more of those criteria included effects from precipitation, evapotranspiration, reservoirs, grazing, irrigation return flow, groundwater discharge, discharge of energy co-produced waters, and stream habitat restoration. In contrast, surface disturbance of naturally salt-rich soil by oil and gas development activities, such as pipeline, road, and well pad construction, is a reasonable candidate for explaining the salinity increase. As development continues to expand in semiarid lands worldwide, the potential for soil disturbance to increase stream salinity should be considered, particularly where soils host substantial quantities of native salts.

  7. Soil disturbance as a driver of increased stream salinity in a semiarid watershed undergoing energy development

    Bern, Carleton R.; Clark, Melanie L.; Schmidt, Travis S.; Holloway, JoAnn M.; McDougal, Robert R.


    Salinization is a global threat to the quality of streams and rivers, but it can have many causes. Oil and gas development were investigated as one of several potential causes of changes in the salinity of Muddy Creek, which drains 2470 km2 of mostly public land in Wyoming, U.S.A. Stream discharge and salinity vary with seasonal snowmelt and define a primary salinity-discharge relationship. Salinity, measured by specific conductance, increased substantially in 2009 and was 53-71% higher at low discharge and 33-34% higher at high discharge for the years 2009-2012 compared to 2005-2008. Short-term processes (e.g., flushing of efflorescent salts) cause within-year deviations from the primary relation but do not obscure the overall increase in salinity. Dissolved elements associated with increased salinity include calcium, magnesium, and sulfate, a composition that points to native soil salts derived from marine shales as a likely source. Potential causes of the salinity increase were evaluated for consistency by using measured patterns in stream chemistry, slope of the salinity-discharge relationship, and inter-annual timing of the salinity increase. Potential causes that were inconsistent with one or more of those criteria included effects from precipitation, evapotranspiration, reservoirs, grazing, irrigation return flow, groundwater discharge, discharge of energy co-produced waters, and stream habitat restoration. In contrast, surface disturbance of naturally salt-rich soil by oil and gas development activities, such as pipeline, road, and well pad construction, is a reasonable candidate for explaining the salinity increase. As development continues to expand in semiarid lands worldwide, the potential for soil disturbance to increase stream salinity should be considered, particularly where soils host substantial quantities of native salts.

  8. Estimating Stream Surface Flow Velocities from Video Clips

    Weijs, S. V.; Brauchli, T.; Chen, Z.; Huwald, H.


    Measuring surface flow velocities in streams can provide important information on discharge. This information is independent of water level, the most commonly used proxy for discharge and therefore has significant potential to reduce uncertainties. Advances in cheap and commonly used imaging devices (e.g. smartphone cameras) and image processing techniques offer new opportunities to get velocity information. Short video clips of streams can be used in combination with optical flow algorithms to get proxies for stream surface velocities. Here some initial results are presented and the main challenges are discussed, especially in view of using these techniques in a citizen science context (specifically the "WeSenseIt" project, a citizen observatory of water), where we try to minimize the need for site preparation and additional equipment needed to take measurements.

  9. Numerical investigation of the spatial scale and time dependency of tile drainage contribution to stream flow

    Thomas, Nicholas W.; Arenas, Antonio A.; Schilling, Keith E.; Weber, Larry J.


    Tile drainage systems are pervasive in the Central U.S., significantly altering the hydrologic system. The purpose of this study was to assess the effects of tile drainage systems on streamflow. A physically based coupled hydrologic model was applied to a 45 km2 agricultural Iowa watershed. Tile drainage was incorporated though an equivalent porous medium approach, calibrated though numerical experimentation. Experimental results indicated that a significant increase in hydraulic conductivity of the equivalent medium layer was needed to achieve agreement in total outflow with an explicit numerical representation of a tiled system. Watershed scale analysis derived the tile drainage contribution to stream flow (QT/Q) from a numerical tracer driven analysis of instream surface water. During precipitation events tile drainage represented 30% of stream flow, whereas during intervals between precipitations events, 61% of stream flow originated from the tile system. A division of event and non-event periods produced strong correlations between QT/Q and drainage area, positive for events, and negative for non-events. The addition of precipitation into the system acted to saturate near surface soils, increase lateral soil water movement, and dilute the relatively stable instream tile flow. Increased intensity precipitation translated the QT/Q relationship downward in a consistent manner. In non-event durations, flat upland areas contributed large contributions of tile flow, diluted by larger groundwater (non-tile) contribution to stream flow in the downstream steeper portion of the watershed. Study results provide new insights on the spatiotemporal response of tile drainage to precipitation and contributions of tile drainage to streamflow at a watershed scale, with results having important implications for nitrate transport.


    Near-stream and upslope soil chemical properties were analyzed to infer linkages between soil and surface water chemistry at the Bear Brook Watershed in Maine [BBWM]. Organic and mineral soil samples were collected along six 20 m transects perpendicular to the stream and one 200 ...

  11. Flow Field and Acoustic Predictions for Three-Stream Jets

    Simmons, Shaun Patrick; Henderson, Brenda S.; Khavaran, Abbas


    Computational fluid dynamics was used to analyze a three-stream nozzle parametric design space. The study varied bypass-to-core area ratio, tertiary-to-core area ratio and jet operating conditions. The flowfield solutions from the Reynolds-Averaged Navier-Stokes (RANS) code Overflow 2.2e were used to pre-screen experimental models for a future test in the Aero-Acoustic Propulsion Laboratory (AAPL) at the NASA Glenn Research Center (GRC). Flowfield solutions were considered in conjunction with the jet-noise-prediction code JeNo to screen the design concepts. A two-stream versus three-stream computation based on equal mass flow rates showed a reduction in peak turbulent kinetic energy (TKE) for the three-stream jet relative to that for the two-stream jet which resulted in reduced acoustic emission. Additional three-stream solutions were analyzed for salient flowfield features expected to impact farfield noise. As tertiary power settings were increased there was a corresponding near nozzle increase in shear rate that resulted in an increase in high frequency noise and a reduction in peak TKE. As tertiary-to-core area ratio was increased the tertiary potential core elongated and the peak TKE was reduced. The most noticeable change occurred as secondary-to-core area ratio was increased thickening the secondary potential core, elongating the primary potential core and reducing peak TKE. As forward flight Mach number was increased the jet plume region decreased and reduced peak TKE.

  12. The role of hillslopes in stream flow response: connectivity, flow path, and transit time

    McGuire, K. J.; McDonnell, J. J.


    Subsurface flow from hillslopes is widely recognized as an important contributor to stream flow generation; however, processes that control how and when hillslopes connect to streams remain unclear. Much of the difficulty in deciphering hillslope response in the stream is due to riparian zone modulation of these inputs. We investigated stream and hillslope runoff dynamics in a 10 ha catchment in the western Cascades of Oregon where the riparian zone has been removed by debris flows, providing an unambiguous hillslope hydrologic signal to the stream channel. Water transit time was used as a framework to develop a conceptual stream flow generation model for the small basin. We based our conceptualization on observations of hydrometric, stable isotope, and applied tracer responses and computed transit times for multiple runoff components using a simple linear systems model. Event water mean transit times (8 to 34 h) and rapid breakthrough from applied hillslope tracer additions, demonstrated that contributing areas extend far upslope during events. Despite rapid hillslope transport processes during events, vadose zone water and runoff mean transit times during non-storm conditions were greater than the timescale of storm events. Vadose zone water mean transit times ranged between 10 and 25 days. Hillslope seepage and catchment baseflow mean transit times were between 1 and 2 years. We describe a conceptual model that captures variable physical flow pathways and transit times through changing antecedent wetness conditions that illustrate the different stages of hillslope and stream connectivity.

  13. Soil disturbance/restoration effects on stream sediment loading in the Tahoe Basin--detection monitoring.

    Grismer, M E


    Quantifying the relative impacts of soil restoration or disturbance on watershed daily sediment and nutrients loads is essential towards assessing the actual costs/benefits of the land management. Such quantification requires stream monitoring programs capable of detecting changes in land-use or soil functional and erosive area "connectivity" conditions across the watershed. Previously, use of a local-scale, field-data based runoff and erosion model for three Lake Tahoe west-shore watersheds as a detection monitoring "proof of concept" suggested that analyses of midrange average daily flows can reveal sediment load reductions of relatively small watershed fractional areas (∼5 %) of restored soil function within a few years of treatment. Developing such an effective stream monitoring program is considered for tributaries on the west shore of the Lake Tahoe Basin using continuous (15-min) stream monitoring information from Ward (2,521 ha), Blackwood (2,886 ha), and the Homewood (260 ha, HMR) Creek watersheds. The continuous total suspended sediment (TSS) and discharge monitoring confirmed the hysteretic TSS concentration-flowrate relationship associated with the daily and seasonal spring snowmelt hydrographs at all three creeks. Using the complete dataset, daily loads estimated from 1-h sampling periods during the day indicated that the optimal sampling hours were in the afternoon during the rising limb of the spring snowmelt hydrograph, an observation likely to apply across the Sierra Nevada and other snowmelt driven watersheds. Measured rising limb sediment loads were used to determine if soils restoration efforts (e.g., dirt road removal, ski run rehabilitation) at the HMR creek watershed reduced sediment loads between 2010 and 2011. A nearly 1.5-fold decrease in sediment yields (kg/ha per m(3)/s flow) was found suggesting that this focused monitoring approach may be useful towards development of TMDL "crediting" tools. Further monitoring is needed to verify

  14. Arbitrary axisymmetric steady streaming: Flow, force and propulsion

    Spelman, Tamsin A


    A well-developed method to induce mixing on microscopic scales is to exploit flows generated by steady streaming. Steady streaming is a classical fluid dynamics phenomenon whereby a time-periodic forcing in the bulk or along a boundary is enhanced by inertia to induce a non-zero net flow. Building on classical work for simple geometrical forcing and motivated by the complex shape oscillations of elastic capsules and bubbles, we develop the mathematical framework to quantify the steady streaming of a spherical body with arbitrary axisymmetric time-periodic boundary conditions. We compute the flow asymptotically for small-amplitude oscillations of the boundary in the limit where the viscous penetration length scale is much smaller than the body. In that case, the flow has a boundary layer structure and the fluid motion is solved by asymptotic matching. Our results, presented in the case of no-slip boundary conditions and extended to include the motion of vibrating free surfaces, recovers classical work as parti...

  15. Perched groundwater-surface interactions and their consequences in stream flow generation in a semi-arid headwater catchment

    Molenat, Jerome; Bouteffeha, Maroua; Raclot, Damien; Bouhlila, Rachida


    In semi-arid headwater catchment, it is usually admitted that stream flow comes predominantly from Hortonian overland flow (infiltration excess overland flow). Consequently, subsurface flow processes, and especially perched or shallow groundwater flow, have not been studied extensively. Here we made the assumption that perched groundwater flow could play a significant role in stream flow generation in semi-arid catchment. To test this assumption, we analyzed stream flow time series of a headwater catchment in the Tunisian Cap Bon region and quantified the flow fraction coming from groundwater discharge and that from overland flow. Furthermore, the dynamics of the perched groundwater was analyzed, by focusing on the different perched groundwater-surface interaction processes : diffuse and local infiltration, diffuse exfiltration, and direct groundwater discharge to the stream channel. This work is based on the 2.6 km² Kamech catchment (Tunisia), which belongs to the long term Mediterranean hydrological observatory OMERE (Voltz and Albergel, 2002). Results show that even though Hortonian overland flow was the main hydrological process governing the stream flow generation, groundwater discharge contribution to the stream channel annually accounted for from 10% to 20 % depending on the year. Furthermore, at some periods, rising of groundwater table to the soil surface in bottom land areas provided evidences of the occurrence of saturation excess overland flow processes during some storm events. Reference Voltz , M. and Albergel , J., 2002. OMERE : Observatoire Méditerranéen de l'Environnement Rural et de l'Eau - Impact des actions anthropiques sur les transferts de masse dans les hydrosystèmes méditerranéens ruraux. Proposition d'Observatoire de Recherche en Environnement, Ministère de la Recherche.

  16. Substantial soil organic carbon retention along floodplains of mountain streams

    Sutfin, Nicholas A.; Wohl, Ellen


    Small, snowmelt-dominated mountain streams have the potential to store substantial organic carbon in floodplain sediment because of high inputs of particulate organic matter, relatively lower temperatures compared with lowland regions, and potential for increased moisture conditions. This work (i) quantifies mean soil organic carbon (OC) content along 24 study reaches in the Colorado Rocky Mountains using 660 soil samples, (ii) identifies potential controls of OC content based on soil properties and spatial position with respect to the channel, and (iii) and examines soil properties and OC across various floodplain geomorphic features in the study area. Stepwise multiple linear regression (adjusted r2 = 0.48, p capture the variability of OC across floodplains in the study area. Mean floodplain OC (6.3 ± 0.3%) is more variable but on average greater than values in uplands (1.5 ± 0.08% to 2.2 ± 0.14%) of the Colorado Front Range and higher than published values from floodplains in other regions, particularly those of larger rivers.

  17. Soil Moisture Data Assimilation in Soil Water Flow Modeling

    Pachepsky, Y. A.; Guber, A.; Jacques, D.; Pan, F.; van Genuchten, M.; Cady, R. E.; Nicholson, T. J.


    Soil water flow modeling has multiple applications. This modeling is based on simplifications stemming from both conceptual uncertainty and lack of detailed knowledge about parameters. Modern soil moisture sensors can provide detailed information about changes in soil water content in time and with depth. This information can be used for data assimilation in soil water flow modeling. The ensemble Kalman filter appears to be an appropriate method for that. Earlier we demonstrated ensemble simulations of soil water flow by using sets of pedotransfer functions (empirical relationships between soil hydraulic properties and soil basic properties, such as particle size distribution, bulk density, organic carbon content, etc.). The objective of this work was to apply the data assimilation with the ensemble Kalman filter to soil water flow modeling, using soil water content monitoring with TDR probes and an ensemble of soil water flow models parameterized with different pedotransfer functions. Experiments were carried out at the Bekkevoort site, Belgium. Sixty time domain reflectometry (TDR) probes with two rods) were installed along the trench in loamy soil at 12 locations with 50-cm horizontal spacing at five depths (15, 35, 55, 75, and 95 cm). Water content and weather parameters were monitored for one year with 15 min frequency. Soil water flow was simulated using the HYDRUS6 software. Mean daily means of water contents at the observation depths were the measurements used in data assimilation. Eighteen pedotransfer functions for water retention and one for hydraulic conductivity were applied to generate ensembles to evaluate the uncertainty in simulation results, whereas the replicated measurements at each of measurement depths were used to characterize the uncertainty in data. Data assimilation appeared to be very efficient. Even assimilating measurements at a single depth provided substantial improvement in simulations at other observation depths. Results on

  18. Reconstruction, prediction and simulation of multiple monthly stream-flow series



    Full Text Available The logarithms of monthly stream-flows are usually found to have a Normal distribution. Stream-flow series are auto-correlated up to a given time lag s. Moreover stream-flow series of the same region are cross correlated.

  19. Three Principles of Water Flow in Soils

    Guo, L.; Lin, H.


    Knowledge of water flow in soils is crucial to understanding terrestrial hydrological cycle, surface energy balance, biogeochemical dynamics, ecosystem services, contaminant transport, and many other Critical Zone processes. However, due to the complex and dynamic nature of non-uniform flow, reconstruction and prediction of water flow in natural soils remain challenging. This study synthesizes three principles of water flow in soils that can improve modeling water flow in soils of various complexity. The first principle, known as the Darcy's law, came to light in the 19th century and suggested a linear relationship between water flux density and hydraulic gradient, which was modified by Buckingham for unsaturated soils. Combining mass balance and the Buckingham-Darcy's law, L.A. Richards quantitatively described soil water change with space and time, i.e., Richards equation. The second principle was proposed by L.A. Richards in the 20th century, which described the minimum pressure potential needed to overcome surface tension of fluid and initiate water flow through soil-air interface. This study extends this principle to encompass soil hydrologic phenomena related to varied interfaces and microscopic features and provides a more cohesive explanation of hysteresis, hydrophobicity, and threshold behavior when water moves through layered soils. The third principle is emerging in the 21st century, which highlights the complex and evolving flow networks embedded in heterogeneous soils. This principle is summarized as: Water moves non-uniformly in natural soils with a dual-flow regime, i.e., it follows the least-resistant or preferred paths when "pushed" (e.g., by storms) or "attracted" (e.g., by plants) or "restricted" (e.g., by bedrock), but moves diffusively into the matrix when "relaxed" (e.g., at rest) or "touched" (e.g., adsorption). The first principle is a macroscopic view of steady-state water flow, the second principle is a microscopic view of interface

  20. Stochastic Modelling of Shiroro River Stream flow Process

    Musa, J. J


    Full Text Available Economists, social scientists and engineers provide insights into the drivers of anthropogenic climate change and the options for adaptation and mitigation, and yet other scientists, including geographers and biologists, study the impacts of climate change. This project concentrates mainly on the discharge from the Shiroro River. A stochastic approach is presented for modeling a time series by an Autoregressive Moving Average model (ARMA. The development and use of a stochastic stream flow model involves some basic steps such as obtain stream flow record and other information, Selecting models that best describes the marginal probability distribution of flows. The flow discharge of about 22 years (1990-2011 was gotten from the Meteorological Station at Shiroro and analyzed with three different models namely; Autoregressive (AR model, Autoregressive Moving Average (ARMA model and Autoregressive Integrated Moving Average (ARIMA model. The initial model identification is done by using the autocorrelation function (ACF and partial autocorrelation function (PACF. Based on the model analysis and evaluations, proper predictions for the effective usage of the flow from the river for farming activities and generation of power for both industrial and domestic us were made. It also highlights some recommendations to be made to utilize the possible potentials of the river effectively

  1. Subsurface lateral flow from hillslope and its contribution to nitrate loading in streams through an agricultural catchment during subtropical rainstorm events

    Zhang, B.; Tang, J. L.; Gao, Ch.; Zepp, H.


    Subsurface lateral flow from agricultural hillslopes is often overlooked compared with overland flow and tile drain flow, partly due to the difficulties in monitoring and quantifying. The objectives of this study were to examine how subsurface lateral flow generated through soil pedons from cropped hillslopes and to quantify its contribution to nitrate loading in the streams through an agricultural catchment in the subtropical region of China. Profiles of soil water potential along hillslopes and stream hydro-chemographs in a trenched stream below a cropped hillslope and at the catchment outlet were simultaneously recorded during two rainstorm events. The dynamics of soil water potential showed positive matrix soil water potential over impermeable soil layer at 0.6 to 1.50 m depths during and after the storms, indicating soil water saturation and drainage processes along the hillslopes irrespective of land uses. The hydro-chemographs in the streams, one trenched below a cropped hillslope and one at the catchment outlet, showed that the concentrations of particulate nitrogen and phosphorus corresponded well to stream flow during the storm, while the nitrate concentration increased on the recession limbs of the hydrographs after the end of the storm. All the synchronous data revealed that nitrate was delivered from the cropped hillslope through subsurface lateral flow to the streams during and after the end of the rainstorms. A chemical mixing model based on electricity conductivity (EC) and H+ concentration was successfully established, particularly for the trenched stream. The results showed that the subsurface lateral flow accounted for 29% to 45% of total stream flow in the trenched stream, responsible for 86% of total NO3--N loss (or 26% of total N loss), and for 5.7% to 7.3% of total stream flow at the catchment outlet, responsible for about 69% of total NO3--N loss (or 28% of total N loss). The results suggest that subsurface lateral flow through hydraulically

  2. Subsurface lateral flow from hillslope and its contribution to nitrate loading in streams through an agricultural catchment during subtropical rainstorm events

    B. Zhang


    Full Text Available Subsurface lateral flow from agricultural hillslopes is often overlooked compared with overland flow and tile drain flow, partly due to the difficulties in monitoring and quantifying. The objectives of this study were to examine how subsurface lateral flow generated through soil pedons from cropped hillslopes and to quantify its contribution to nitrate loading in the streams through an agricultural catchment in the subtropical region of China. Profiles of soil water potential along hillslopes and stream hydro-chemographs in a trenched stream below a cropped hillslope and at the catchment outlet were simultaneously recorded during two rainstorm events. The dynamics of soil water potential showed positive matrix soil water potential over impermeable soil layer at 0.6 to 1.50 m depths during and after the storms, indicating soil water saturation and drainage processes along the hillslopes irrespective of land uses. The hydro-chemographs in the streams, one trenched below a cropped hillslope and one at the catchment outlet, showed that the concentrations of particulate nitrogen and phosphorus corresponded well to stream flow during the storm, while the nitrate concentration increased on the recession limbs of the hydrographs after the end of the storm. All the synchronous data revealed that nitrate was delivered from the cropped hillslope through subsurface lateral flow to the streams during and after the end of the rainstorms. A chemical mixing model based on electricity conductivity (EC and H+ concentration was successfully established, particularly for the trenched stream. The results showed that the subsurface lateral flow accounted for 29% to 45% of total stream flow in the trenched stream, responsible for 86% of total NO3-N loss (or 26% of total N loss, and for 5.7% to 7.3% of total stream flow at the catchment outlet, responsible for about 69% of total NO3-N loss (or 28% of total N

  3. Linking the field to the stream: soil erosion and sediment yield in a rural catchment, NW Spain

    Rodriguez-Blanco, M. L.; Taboada-Castro, M. M.; Palleiro-Suarez, L.; Taboada-Castro, M. T.


    Quantifying the linkages between field erosion, fluvial response and catchment sediment yield remains problematic, among other reasons, because of the re-deposition of eroded sediment within the catchment, which is controlled by the spatial organization of the land use and the connectivity between sediment sources and the stream network. This paper presents the results of an integrated study that considered the relationship between erosion and stream sediment yield in an agroforestry catchment (16 km2) in NW Spain. The geology consists of basic metamorphic schist. The relieve of the area is steeper, the mean slope is approximately 19%. Main soil types are classified as Umbrisol and Cambisol. Soils are acidic and rich in organic matter. The soil texture is silt and silt-loam. Land cover consists of a mixture of forest (65%) and agricultural fields (mainly grassland, pasture and maize). The study combined measurements of soil erosion by concentrate flow and sediment deposition at field scale with sediment yield measured at the catchment outlet. The hydrological data and water samples were obtained at the catchment outlet. Stream water level was monitored continuously and converted to discharge using a rating curve. The sampling for suspended sediments was supplemented by an automatic sampler. Suspended sediment load was calculated from the suspended sediment concentrations and discharge data. Eroded volume was calculated from cross-sections (measured at specific points, where the section changed abruptly) and length of the channel segments. The total sediment delivered to stream was determined as the difference between all erosion features (rills and gullies) and the sediment volumes that were deposited on the fields. The results showed that in the catchment during the period winter 2007/08 soil erosion by concentrate flow, i.e. rills and ephemeral gullies, occurred on unprotected crop field. Erosion by concentrate flow was highly discontinuous within the catchment

  4. Fire, flow and dynamic equilibrium in stream macroinvertebrate communities

    Arkle, R.S.; Pilliod, D.S.; Strickler, K.


    The complex effects of disturbances on ecological communities can be further complicated by subsequent perturbations within an ecosystem. We investigated how wildfire interacts with annual variations in peak streamflow to affect the stability of stream macroinvertebrate communities in a central Idaho wilderness, USA. We conducted a 4-year retrospective analysis of unburned (n = 7) and burned (n = 6) catchments, using changes in reflectance values (??NBR) from satellite imagery to quantify the percentage of each catchment's riparian and upland vegetation that burned at high and low severity. For this wildland fire complex, increasing riparian burn severity and extent were associated with greater year-to-year variation, rather than a perennial increase, in sediment loads, organic debris, large woody debris (LWD) and undercut bank structure. Temporal changes in these variables were correlated with yearly peak flow in burned catchments but not in unburned reference catchments, indicating that an interaction between fire and flow can result in decreased habitat stability in burned catchments. Streams in more severely burned catchments exhibited increasingly dynamic macroinvertebrate communities and did not show increased similarity to reference streams over time. Annual variability in macroinvertebrates was attributed, predominantly, to the changing influence of sediment, LWD, riparian cover and organic debris, as quantities of these habitat components fluctuated annually depending on burn severity and annual peak streamflows. These analyses suggest that interactions among fire, flow and stream habitat may increase inter-annual habitat variability and macroinvertebrate community dynamics for a duration approaching the length of the historic fire return interval of the study area. ?? 2009 Blackwell Publishing Ltd.

  5. Determination of trunk streams via using flow accumulation values

    Farek, Vladimir


    There is often a problem, with schematisation of catchments and a channel networks in a broken relief like sandstone landscape (with high vertical segmentation, narrow valley lines, crags, sheer rocks, endorheic hollows etc.). Usual hydrological parameters (subcatchment areas, altitude of highest point of subcatchment, water discharge), which are mostly used for determination of trunk stream upstream the junction, are frequently not utilizable very well in this kind of relief. We found, that for small, relatively homogeneous catchments (within the meaning of land-use, geological subsurface, anthropogenic influence etc.), which are extremely shaped, the value called "flow accumulation" (FA) could be very useful. This value gives the number of cells of the Digital Elevation Model (DEM) grid, which are drained to each cell of the catchment. We can predict that the stream channel with higher values of flow accumulation represents the main stream. There are three crucial issues with this theory. At first it is necessary to find the most suitable algorithm for calculation flow accumulation in a broken relief. Various algorithms could have complications with correct flow routing (representation of divergent or convergent character of the flow), or with keeping the flow paths uninterrupted. Relief with high curvature changes (alternating concave/convex shapes, high steepness changes) causes interrupting of flow lines in many algorithms used for hydrological computing. Second - set down limits of this theory (e.g. the size and character of a surveyed catchment). Third - verify this theory in reality. We tested this theory on sandstone landscape of National park Czech Switzerland. The main data source were high-resolution LIDAR (Light Detection and Ranging) DEM snapshots of surveyed area. This data comes from TU Dresden project called Genesis (Geoinformation Networks For The Cross- Border National Park Region Saxon- Bohemian Switzerland). In order to solve these issues GIS

  6. Shock formation and structure in magnetic reconnection with a streaming flow.

    Wu, Liangneng; Ma, Zhiwei; Zhang, Haowei


    The features of magnetic reconnection with a streaming flow have been investigated on the basis of compressible resistive magnetohydrodynamic (MHD) model. The super-Alfvenic streaming flow largely enhances magnetic reconnection. The maximum reconnection rate is almost four times larger with super-Alfvenic streaming flow than sub-Alfvénic streaming flow. In the nonlinear stage, it is found that there is a pair of shocks observed in the inflow region, which are manifested to be slow shocks for sub-Alfvénic streaming flow, and fast shocks for super-Alfvénic streaming flow. The quasi-period oscillation of reconnection rates in the decaying phase for super-Alfvénic streaming flow is resulted from the different drifting velocities of the shock and the X point.

  7. Estimates of Flow Duration, Mean Flow, and Peak-Discharge Frequency Values for Kansas Stream Locations

    Perry, Charles A.; Wolock, David M.; Artman, Joshua C.


    Streamflow statistics of flow duration and peak-discharge frequency were estimated for 4,771 individual locations on streams listed on the 1999 Kansas Surface Water Register. These statistics included the flow-duration values of 90, 75, 50, 25, and 10 percent, as well as the mean flow value. Peak-discharge frequency values were estimated for the 2-, 5-, 10-, 25-, 50-, and 100-year floods. Least-squares multiple regression techniques were used, along with Tobit analyses, to develop equations for estimating flow-duration values of 90, 75, 50, 25, and 10 percent and the mean flow for uncontrolled flow stream locations. The contributing-drainage areas of 149 U.S. Geological Survey streamflow-gaging stations in Kansas and parts of surrounding States that had flow uncontrolled by Federal reservoirs and used in the regression analyses ranged from 2.06 to 12,004 square miles. Logarithmic transformations of climatic and basin data were performed to yield the best linear relation for developing equations to compute flow durations and mean flow. In the regression analyses, the significant climatic and basin characteristics, in order of importance, were contributing-drainage area, mean annual precipitation, mean basin permeability, and mean basin slope. The analyses yielded a model standard error of prediction range of 0.43 logarithmic units for the 90-percent duration analysis to 0.15 logarithmic units for the 10-percent duration analysis. The model standard error of prediction was 0.14 logarithmic units for the mean flow. Regression equations used to estimate peak-discharge frequency values were obtained from a previous report, and estimates for the 2-, 5-, 10-, 25-, 50-, and 100-year floods were determined for this report. The regression equations and an interpolation procedure were used to compute flow durations, mean flow, and estimates of peak-discharge frequency for locations along uncontrolled flow streams on the 1999 Kansas Surface Water Register. Flow durations, mean

  8. Ice and thermal cameras for stream flow observations

    Tauro, Flavia; Petroselli, Andrea; Grimaldi, Salvatore


    Flow measurements are instrumental to establish discharge rating curves and to enable flood risk forecast. Further, they are crucial to study erosion dynamics and to comprehend the organization of drainage networks in natural catchments. Flow observations are typically executed with intrusive instrumentation, such as current meters or acoustic devices. Alternatively, non-intrusive instruments, such as radars and microwave sensors, are applied to estimate surface velocity. Both approaches enable flow measurements over areas of limited extent, and their implementation can be costly. Optical methods, such as large scale particle image velocimetry, have proved beneficial for non-intrusive and spatially-distributed environmental monitoring. In this work, a novel optical-based approach is utilized for surface flow velocity observations based on the combined use of a thermal camera and ice dices. Different from RGB imagery, thermal images are relatively unaffected by illumination conditions and water reflections. Therefore, such high-quality images allow to readily identify and track tracers against the background. Further, the optimal environmental compatibility of ice dices and their relative ease of preparation and storage suggest that the technique can be easily implemented to rapidly characterize surface flows. To demonstrate the validity of the approach, we present a set of experiments performed on the Brenta stream, Italy. In the experimental setup, the axis of the camera is maintained perpendicular with respect to the water surface to circumvent image orthorectification through ground reference points. Small amounts of ice dices are deployed onto the stream water surface during image acquisition. Particle tracers' trajectories are reconstructed off-line by analyzing thermal images with a particle tracking velocimetry (PTV) algorithm. Given the optimal visibility of the tracers and their low seeding density, PTV allows for efficiently following tracers' paths in

  9. Trends in peak flows of selected streams in Kansas

    Rasmussen, T.J.; Perry, C.A.


    The possibility of a systematic change in flood potential led to an investigation of trends in the magnitude of annual peak flows in Kansas. Efficient design of highway bridges and other flood-plain structures depends on accurate understanding of flood characteristics. The Kendall's tau test was used to identify trends at 40 stream-gaging stations during the 40-year period 1958-97. Records from 13 (32 percent) of the stations showed significant trends at the 95-percent confidence level. Only three of the records (8 percent) analyzed had increasing trends, whereas 10 records (25 percent) had decreasing trends, all of which were for stations located in the western one-half of the State. An analysis of flow volume using mean annual discharge at 29 stations in Kansas resulted in 6 stations (21 percent) with significant trends in flow volumes. All six trends were decreasing and occurred in the western one-half of the State. The Kendall's tau test also was used to identify peak-flow trends over the entire period of record for 54 stream-gaging stations in Kansas. Of the 23 records (43 percent) showing significant trends, 16 (30 percent) were decreasing, and 7 (13 percent) were increasing. The trend test then was applied to 30-year periods moving in 5-year increments to identify time periods within each station record when trends were occurring. Systematic changes in precipitation patterns and long-term declines in ground-water levels in some stream basins may be contributing to peak-flow trends. To help explain the cause of the streamflow trends, the Kendall's tau test was applied to total annual precipitation and ground-water levels in Kansas. In western Kansas, the lack of precipitation and presence of decreasing trends in ground-water levels indicated that declining water tables are contributing to decreasing trends in peak streamflow. Declining water tables are caused by ground-water withdrawals and other factors such as construction of ponds and terraces. Peak-flow

  10. Stream biofilm responses to flow intermittency: from cells to ecosystems

    Sergi eSabater


    Full Text Available Temporary streams are characterized by the alternation of dry and wet hydrological phases, creating both a harsh environment for the biota as well as a high diversity of opportunities for adaptation. These systems are eminently microbial-based during several of these hydrological phases, and those growing on all solid substrata (biofilms accordingly change their physical structure and community composition. Biofilms experience large decreases on cell densities and biomass, both of bacteria and algae, during dryness. Algal and bacterial communities show remarkable decreases in their diversity, at least locally (at the habitat scale. Biofilms also respond with significant physiological plasticity to each of the hydrological changes. The decreasing humidity of the substrata through the drying process, and the changing quantity and quality of organic matter and nutrients available in the stream during that process, causes unequal responses on the biofilm bacteria and algae. Biofilm algae are affected faster than bacteria by the hydric stress, and as a result the ecosystem respiration resists longer than gross primary production to the increasing duration of flow intermittency. This response implies enhancing ecosystem heterotrophy, a pattern that can be exacerbated in temporary streams suffering of longer dry periods under global change.

  11. The effect of in-stream activities on the Njoro River, Kenya. Part I: Stream flow and chemical water quality

    Yillia, Paul T.; Kreuzinger, Norbert; Mathooko, Jude M.

    For shallow streams in sub-Saharan Africa, in-stream activities could be described as the actions by people and livestock, which take place within or besides stream channels. This study examined the nature of in-stream activities along a rural stream in Kenya and established the inequality in water allocation for various livelihood needs, as well as the negative impact they have on dry weather stream flow and chemical water quality. Seven locations along the stream were studied in wet and dry weather of 2006. Enumeration consisted of making head counts of people and livestock and tallying visitors at hourly intervals from 6 a.m. to 7 p.m. To estimate water abstraction, filled containers of known volume were counted and the stream was sampled to examine the impact on water quality. Water samples were obtained upstream and downstream of in-stream activities before (6 a.m.) and during (11 a.m., 6 p.m.) activities. Samples were analyzed for suspended solids, turbidity, BOD 5, total nitrogen and total phosphorus. The daily total abstraction at the middle reaches during dry weather was 120-150 m 3 day -1. More than 60% of abstraction was done by water vendors. Vended water from the stream was sold at US 3.5-7.5 per m 3 and vendors earned between US 3-6 a day. Abstracted water contributed approximately 40-60% of the total daily consumptive water use in the riparian area during dry weather but >30% of the morning stream flow was abstracted thereby upsetting stream flow in the lower reaches. The daily total water abstraction correlated positively ( R2, 0.98) and significantly ( p management strategy on the livelihoods of the riparian inhabitants.

  12. Convection and fluidization in oscillatory granular flows: The role of acoustic streaming.

    Valverde, Jose Manuel


    Convection and fluidization phenomena in vibrated granular beds have attracted a strong interest from the physics community since the last decade of the past century. As early reported by Faraday, the convective flow of large inertia particles in vibrated beds exhibits enigmatic features such as frictional weakening and the unexpected influence of the interstitial gas. At sufficiently intense vibration intensities surface patterns appear bearing a stunning resemblance with the surface ripples (Faraday waves) observed for low-viscosity liquids, which suggests that the granular bed transits into a liquid-like fluidization regime despite the large inertia of the particles. In his 1831 seminal paper, Faraday described also the development of circulation air currents in the vicinity of vibrating plates. This phenomenon (acoustic streaming) is well known in acoustics and hydrodynamics and occurs whenever energy is dissipated by viscous losses at any oscillating boundary. The main argument of the present paper is that acoustic streaming might develop on the surface of the large inertia particles in the vibrated granular bed. As a consequence, the drag force on the particles subjected to an oscillatory viscous flow is notably enhanced. Thus, acoustic streaming could play an important role in enhancing convection and fluidization of vibrated granular beds, which has been overlooked in previous studies. The same mechanism might be relevant to geological events such as fluidization of landslides and soil liquefaction by earthquakes and sound waves.

  13. Methods for estimating selected low-flow frequency statistics and harmonic mean flows for streams in Iowa

    Eash, David A.; Barnes, Kimberlee K.


    characteristics, landform regions, and soil regions. A comparison of root mean square errors and average standard errors of prediction for the statewide, regional, and region-of-influence regressions determined that the regional regression provided the best estimates of the seven selected statistics at ungaged sites in Iowa. Because a significant number of streams in Iowa reach zero flow as their minimum flow during low-flow years, four different types of regression analyses were used: left-censored, logistic, generalized-least-squares, and weighted-least-squares regression. A total of 192 streamgages were included in the development of 27 regression equations for the three low-flow regions. For the northeast and northwest regions, a censoring threshold was used to develop 12 left-censored regression equations to estimate the 6 low-flow frequency statistics for each region. For the southern region a total of 12 regression equations were developed; 6 logistic regression equations were developed to estimate the probability of zero flow for the 6 low-flow frequency statistics and 6 generalized least-squares regression equations were developed to estimate the 6 low-flow frequency statistics, if nonzero flow is estimated first by use of the logistic equations. A weighted-least-squares regression equation was developed for each region to estimate the harmonic-mean-flow statistic. Average standard errors of estimate for the left-censored equations for the northeast region range from 64.7 to 88.1 percent and for the northwest region range from 85.8 to 111.8 percent. Misclassification percentages for the logistic equations for the southern region range from 5.6 to 14.0 percent. Average standard errors of prediction for generalized least-squares equations for the southern region range from 71.7 to 98.9 percent and pseudo coefficients of determination for the generalized-least-squares equations range from 87.7 to 91.8 percent. Average standard errors of prediction for weighted

  14. Bubble size prediction in co-flowing streams

    van Hoeve, Wim; Gordillo, José M; Versluis, Michel; Lohse, Detlef


    In this paper, the size of bubbles formed through the breakup of a gaseous jet in a co-axial microfluidic device is derived. The gaseous jet surrounded by a co-flowing liquid stream breaks up into monodisperse microbubbles and the size of the bubbles is determined by the radius of the inner gas jet and the bubble formation frequency. We obtain the radius of the gas jet by solving the Navier-Stokes equations for low Reynolds number flows and by minimization of the dissipation energy. The prediction of the bubble size is based on the system's control parameters only, i.e. the inner gas flow rate $Q_i$, the outer liquid flow rate $Q_o$, and the tube radius $R$. For a very low gas-to-liquid flow rate ratio ($Q_i / Q_o \\rightarrow 0$) the bubble radius scales as $r_b / R \\propto \\sqrt{Q_i / Q_o}$, independently of the inner to outer viscosity ratio $\\eta_i/\\eta_o$ and of the type of the velocity profile in the gas, which can be either flat or parabolic, depending on whether high-molecular-weight surfactants cover ...

  15. Development of stream-subsurface flow module in sub-daily simulation of Escherichia coli using SWAT

    Kim, Minjeong; Boithias, Laurie; Cho, Kyung Hwa; Silvera, Norbert; Thammahacksa, Chanthamousone; Latsachack, Keooudone; Rochelle-Newall, Emma; Sengtaheuanghoung, Oloth; Pierret, Alain; Pachepsky, Yakov A.; Ribolzi, Olivier


    Water contaminated with pathogenic bacteria poses a large threat to public health, especially in the rural areas in the tropics where sanitation and drinking water facilities are often lacking. Several studies have used the Soil and Water Assessment Tool (SWAT) to predict the export of in-stream bacteria at a watershed-scale. However, SWAT is limited to in-stream processes, such as die-off, resuspension and, deposition; and it is usually implemented on a daily time step using the SCS Curve Number method, making it difficult to explore the dynamic fate and transport of bacteria during short but intense events such as flash floods in tropical humid montane headwaters. To address these issues, this study implemented SWAT on an hourly time step using the Green-Ampt infiltration method, and tested the effects of subsurface flow (LATQ+GWQ in SWAT) on bacterial dynamics. We applied the modified SWAT model to the 60-ha Houay Pano catchment in Northern Laos, using sub-daily rainfall and discharge measurements, electric conductivity-derived fractions of overland and subsurface flows, suspended sediments concentrations, and the number of fecal indicator organism Escherichia coli monitored at the catchment outlet from 2011 to 2013. We also took into account land use change by delineating the watershed with the 3-year composite land use map. The results show that low subsurface flow of less than 1 mm recovered the underestimation of E. coli numbers during the dry season, while high subsurface flow caused an overestimation during the wet season. We also found that it is more reasonable to apply the stream-subsurface flow interaction to simulate low in-stream bacteria counts. Using fecal bacteria to identify and understand the possible interactions between overland and subsurface flows may well also provide some insight into the fate of other bacteria, such as those involved in biogeochemical fluxes both in-stream and in the adjacent soils and hyporheic zones.

  16. Dissolved organic matter composition of winter stream flow in the Yukon River basin

    O'Donnell, J.; Aiken, G.; Walvoord, M. A.; Butler, K.


    In the Yukon River Basin (YRB), groundwater-to-stream discharge has increased by 0.7-0.9% yr-1 over the last three decades, and is likely in response to regional climate warming and permafrost thaw. This recent shift in watershed hydrology has important implications for the flux of dissolved organic matter (DOM) from terrestrial to freshwater and marine ecosystems and its composition. For instance, it has been hypothesized that permafrost thaw and increased groundwater discharge may account for the long-term decline in discharge-normalized dissolved organic carbon (DOC) export in the main stem of the Yukon River. However, the response of DOC dynamics in YRB subcatchments to recent warming and thaw will likely vary over space and time as a function of vegetation, parent material, ground ice content and disturbance history. To evaluate spatial patterns of groundwater DOM composition, we collected under-ice samples during winter flow from 68 streams in the YRB. Using a suite of conservative tracers (specific conductivity, base cations), we also separated the relative contribution of supra- and sub-permafrost groundwaters to winter flow. In general, DOC concentration in winter stream flow was low relative to summer flow, averaging 3.94 ± 0.46 and 18.39 ± 1.39 mg L-1. However, DOM composition varied widely across the YRB, indicating a broad range of organic matter quality and reactivity present for different groundwater sources. In streams receiving inputs primarily from sub-permafrost groundwater, we observed low specific ultraviolet absorbance (SUVA254) values (0.4-1.1 L mgC-1 m-1), a high proportion of hydrophilic compounds (35-50%), and a large proportion of protein-like compounds (13-35%, as determined by fluorescence spectroscopy). In streams where winter flow was a mixture of supra- and sub-permafrost groundwater sources, we observed higher SUVA254 values (2.0-3.6 L mgC-1 m-1), high hydrophobic acid content (43 ± 1%), and small proportion of protein

  17. An Assessment of Mean Areal Precipitation Methods on Simulated Stream Flow: A SWAT Model Performance Assessment

    Sean Zeiger


    Full Text Available Accurate mean areal precipitation (MAP estimates are essential input forcings for hydrologic models. However, the selection of the most accurate method to estimate MAP can be daunting because there are numerous methods to choose from (e.g., proximate gauge, direct weighted average, surface-fitting, and remotely sensed methods. Multiple methods (n = 19 were used to estimate MAP with precipitation data from 11 distributed monitoring sites, and 4 remotely sensed data sets. Each method was validated against the hydrologic model simulated stream flow using the Soil and Water Assessment Tool (SWAT. SWAT was validated using a split-site method and the observed stream flow data from five nested-scale gauging sites in a mixed-land-use watershed of the central USA. Cross-validation results showed the error associated with surface-fitting and remotely sensed methods ranging from −4.5 to −5.1%, and −9.8 to −14.7%, respectively. Split-site validation results showed the percent bias (PBIAS values that ranged from −4.5 to −160%. Second order polynomial functions especially overestimated precipitation and subsequent stream flow simulations (PBIAS = −160 in the headwaters. The results indicated that using an inverse-distance weighted, linear polynomial interpolation or multiquadric function method to estimate MAP may improve SWAT model simulations. Collectively, the results highlight the importance of spatially distributed observed hydroclimate data for precipitation and subsequent steam flow estimations. The MAP methods demonstrated in the current work can be used to reduce hydrologic model uncertainty caused by watershed physiographic differences.

  18. Rehabilitation of a debris-flow prone mountain stream in southwestern China - Strategies, effects and implications

    Yu, Guo-an; Huang, He Qing; Wang, Zhaoyin; Brierley, Gary; Zhang, Kang


    SummaryRehabilitation of Shengou Creek, a small, steep mountain stream in southwestern China that is prone to debris flows, started more than 30 years ago through an integrated program of engineering applications (check dams and guiding dikes), biological measures (reforestation), and social measures (reducing human disturbance). Small and medium-sized check dams and guiding dikes were constructed on key upper and middle sections of the creek to stabilize hillslopes and channel bed. Meanwhile, Leucaena leucocephala, a drought-tolerant, fast-growing, and highly adaptive plant species, was introduced to promote vegetation recovery in the watershed. The collective community structure of tree, shrub, and herb assemblages in the artificial L. leucocephala forest, which developed after 7 years, enhanced soil structure and drastically reduced soil erosion on hillslopes. Cultivation of steep land was strictly controlled in the basin, and some inhabitants were encouraged to move from upstream areas to downstream towns to reduce disturbance. These integrated measures reduced sediment supply from both hillslopes and upstream channels, preventing sediment-related hazards. The development of natural streambed resistance structures (mainly step-pool systems) and luxuriant riparian vegetation aided channel stability, diversity of stream habitat, and ecological maintenance in the creek. These findings are compared with Jiangjia and Xiaobaini Ravines, two adjacent non-rehabilitated debris-flow streams which have climate and geomorphologic conditions similar to Shengou Creek. Habitat diversity indices, taxa richness, biodiversity, and bio-community indices are much higher in Shengou Creek relative to Jiangjia and Xiaobaini Ravines, attesting to the effectiveness of rehabilitation measures.

  19. High levels of endocrine pollutants in US streams during low flow due to insufficient wastewater dilution

    Rice, Jacelyn; Westerhoff, Paul


    Wastewater discharges from publicly owned treatment works are a significant source of endocrine disruptors and other contaminants to the aquatic environment in the US. Although remaining pollutants in wastewater pose environmental risks, treated wastewater is also a primary source of stream flow, which in turn is critical in maintaining many aquatic and riparian wildlife habitats. Here we calculate the dilution factor--the ratio of flow in the stream receiving discharge to the flow of wastewater discharge--for over 14,000 receiving streams in the continental US using streamflow observations and a spatially explicit watershed-scale hydraulic model. We found that wastewater discharges make up more than 50% of in-stream flow for over 900 streams. However, in 1,049 streams that experienced exceptional low-flow conditions, the dilution factors in 635 of those streams fell so low during those conditions that the safety threshold for concentrations of one endocrine disrupting compound was exceeded, and in roughly a third of those streams, the threshold was exceeded for two compounds. We suggest that streams are vulnerable to public wastewater discharge of contaminants under low-flow conditions, at a time when wastewater discharges are likely to be most important for maintaining stream flow for smaller sized river systems.

  20. Adequacy of satellite derived rainfall data for stream flow modeling

    Artan, G.; Gadain, Hussein; Smith, Jody L.; Asante, Kwasi; Bandaragoda, C.J.; Verdin, J.P.


    Floods are the most common and widespread climate-related hazard on Earth. Flood forecasting can reduce the death toll associated with floods. Satellites offer effective and economical means for calculating areal rainfall estimates in sparsely gauged regions. However, satellite-based rainfall estimates have had limited use in flood forecasting and hydrologic stream flow modeling because the rainfall estimates were considered to be unreliable. In this study we present the calibration and validation results from a spatially distributed hydrologic model driven by daily satellite-based estimates of rainfall for sub-basins of the Nile and Mekong Rivers. The results demonstrate the usefulness of remotely sensed precipitation data for hydrologic modeling when the hydrologic model is calibrated with such data. However, the remotely sensed rainfall estimates cannot be used confidently with hydrologic models that are calibrated with rain gauge measured rainfall, unless the model is recalibrated. ?? Springer Science+Business Media, Inc. 2007.

  1. Stream flow regime of springs in the Mantiqueira Mountain Range region, Minas Gerais State

    Alisson Souza de Oliveira


    Full Text Available The stream flow regime of four springs located in the Mantiqueira Mountain Range region (MG was evaluated and correlated to the respective recharge area, relief characteristics, land cover and physical and hydrologic soil characteristics. The streamflow regime was characterized by monitoring of discharges, calculating the surface runoff and specific discharge and by modeling the discharge over the recession period using the Maillet method. As all recharge areas have similar relief the effect of it on the streamflow was not possible to identify. Analysis included determining the effect of drainage area size, soil characteristics and land cover on the indicators of the streamflow regime. Size of the recharge area had a positive influence on the indicators mean discharge and surface runoff volume and on the regulation of the streamflow regime (springs L4 and L1. The spring under the smallest area of influence provided the worst results for the above mentioned indicators (spring L3. The effect of forest cover (natural and planted, associated with soil characteristics, was evidenced by the indicators surface runoff (in depth and specific yield, both independent of the recharge area size (springs L4 and L2. The interaction of area size, soil characteristics and forest cover (natural and planted provided the best results for all indicators of streamflow regime in the springs studied in the Mantiqueira Mountain Range (spring L4.

  2. Quantifying Flow Resistance of Mountain Streams Using the HHT Approach

    Zhang, L.; Fu, X.


    This study quantifies the flow resistance of mountain streams with gravel bed and remarkable bed forms. The motivation is to follow the previous ideas (Robert, A. 1990) that the bed surface can be divided into micro-scale and macro-scale roughness, respectively. We processed the field data of longitudinal bed profiles of the Longxi River, Sichuan Province, China, using the Hilbert-Huang Transformation Method (HHT). Each longitudinal profile was decomposed into a set of curves with different frequencies of spatial fluctuation. The spectrogram was accordingly obtained. We supposed that a certain high and low frequency curves correspond to the micro- and macro-roughness of stream bed, respectively. We specified the characteristic height and length with the spectrogram, which represent the macro bed form accounting for bed form roughness. We then estimated the bed form roughness as being proportional to the ratio of the height to length multiplied by the height(Yang et al,2005). We also assumed the parameter, Sp, defined as the sinuosity of the highest frequency curve as the measure of the micro-scale roughness. We then took into account the effect of bed material sizes through using the product of d50/R and Sp, where d50 is the sediment median size and R is the hydraulic radius. The macro- and micro-scale roughness parameters were merged together nonlinearly to evaluate the flow resistance caused by the interplaying friction and form drag forces. Validation results show that the square of the determinant coefficient can reach as high as 0.84 in the case of the Longxi River. Future studies will focus on the verification against more field data as well as the combination of skin friction and form drag. Key words: flow resistance; roughness; HHT; spectrogram; form drag Robert, A. (1990), Boundary roughness in coarse-grained channels, Prog. Phys. Geogr., 14(1), 42-69. Yang, S.-Q., S.-K. Tan, and S.-Y. Lim. (2005), Flow resistance and bed form geometry in a wide alluvial

  3. Monitoring strategies of stream phosphorus under contrasting climate-driven flow regimes

    Goyenola, Guillermo; Meerhoff, Marianna; Teixeira-de Mello, Franco;


    and the performance of alternative monitoring strategies in streams under contrasting climate-driven flow regimes. We compared a set of paired streams draining lowland micro-catchments under temperate climate and stable discharge conditions (Denmark) and under sub-tropical climate and flashy conditions (Uruguay). We...... phosphorus export from diffuse sources in streams in Uruguay streams, mostly as a consequence of higher variability in flow regime (higher flashiness). Contrarily, we found a higher contribution of dissolved P in flashy streams. We did not find a notably poorer performance of the low-frequency sampling...... program to estimate P exports in flashy streams compared to the less variable streams. We also found signs of interaction between climate/hydrology and land use intensity, in particular in the presence of point sources of P, leading to a bias towards underestimation of P in hydrologically stable streams...

  4. Factors influencing the stream-aquifer flow exchange coefficient.

    Morel-Seytoux, Hubert J; Mehl, Steffen; Morgado, Kyle


    Knowledge of river gain from or loss to a hydraulically connected water table aquifer is crucial in issues of water rights and also when attempting to optimize conjunctive use of surface and ground waters. Typically in groundwater models this exchange flow is related to a difference in head between the river and some point in the aquifer, through a "coefficient." This coefficient has been defined differently as well as the location for the head in the aquifer. This paper proposes a new coefficient, analytically derived, and a specific location for the point where the aquifer head is used in the difference. The dimensionless part of the coefficient is referred to as the SAFE (stream-aquifer flow exchange) dimensionless conductance. The paper investigates the factors that influence the value of this new conductance. Among these factors are (1) the wetted perimeter of the cross-section, (2) the degree of penetration of the cross-section, and (3) the shape of the cross-section. The study shows that these factors just listed are indeed ordered in their respective level of importance. In addition the study verifies that the analytical correct value of the coefficient is matched by finite difference simulation only if the grid system is sufficiently fine. Thus the use of the analytical value of the coefficient is an accurate and efficient alternative to ad hoc estimates for the coefficient typically used in finite difference and finite element methods. © 2013, National Ground Water Association.

  5. Directional movement in response to altered flow in six lowland stream Trichoptera

    Verdonschot, P.F.M.; Besse-Lototskaya, A.A.; Dekkers, T.B.M.; Verdonschot, R.C.M.


    Understanding the trait adaptations associated with mobility in Trichoptera larvae under different flow conditions would enhance the understanding of survival mechanisms under flow stress induced by spates. In stream mesocosms, we mimicked a lowland stream spate by suddenly increasing current veloci

  6. Estimating Flow-Duration and Low-Flow Frequency Statistics for Unregulated Streams in Oregon

    Risley, John; Stonewall, Adam J.; Haluska, Tana


    Flow statistical datasets, basin-characteristic datasets, and regression equations were developed to provide decision makers with surface-water information needed for activities such as water-quality regulation, water-rights adjudication, biological habitat assessment, infrastructure design, and water-supply planning and management. The flow statistics, which included annual and monthly period of record flow durations (5th, 10th, 25th, 50th, and 95th percent exceedances) and annual and monthly 7-day, 10-year (7Q10) and 7-day, 2-year (7Q2) low flows, were computed at 466 streamflow-gaging stations at sites with unregulated flow conditions throughout Oregon and adjacent areas of neighboring States. Regression equations, created from the flow statistics and basin characteristics of the stations, can be used to estimate flow statistics at ungaged stream sites in Oregon. The study area was divided into 10 regression modeling regions based on ecological, topographic, geologic, hydrologic, and climatic criteria. In total, 910 annual and monthly regression equations were created to predict the 7 flow statistics in the 10 regions. Equations to predict the five flow-duration exceedance percentages and the two low-flow frequency statistics were created with Ordinary Least Squares and Generalized Least Squares regression, respectively. The standard errors of estimate of the equations created to predict the 5th and 95th percent exceedances had medians of 42.4 and 64.4 percent, respectively. The standard errors of prediction of the equations created to predict the 7Q2 and 7Q10 low-flow statistics had medians of 51.7 and 61.2 percent, respectively. Standard errors for regression equations for sites in western Oregon were smaller than those in eastern Oregon partly because of a greater density of available streamflow-gaging stations in western Oregon than eastern Oregon. High-flow regression equations (such as the 5th and 10th percent exceedances) also generally were more accurate

  7. Flow Dynamics and Stability of the NE Greenland Ice Stream from Active Seismics and Radar

    Riverman, K. L.; Alley, R. B.; Anandakrishnan, S.; Christianson, K. A.; Peters, L. E.; Muto, A.


    We find that dilatant till facilitates rapid ice flow in central Greenland, and regions of dryer till limit the expansion of ice flow. The Northeast Greenland Ice Stream (NEGIS) is the largest ice stream in Greenland, draining 8.4% of the ice sheet's area. Fast ice flow initiates near the ice sheet summit in a region of high geothermal heat flow and extends some 700km downstream to three outlet glaciers along the NE Coast. The flow pattern and stability mechanism of this ice stream are unique to others in Greenland and Antarctica, and merit further study to ascertain the sensitivity of this ice stream to future climate change. In this study, we present the results of the first-ever ground-based geophysical survey of the initiation zone of NEGIS. Based on radar and preliminary seismic data, Christianson et al. (2014, EPSL) propose a flow mechanism for the ice stream based on topographically driven hydropotential lows which generate 'sticky' regions of the bed under the ice stream margins. We further test this hypothesis using a 40km reflection seismic survey across both ice stream margins. We find that regions of 'sticky' bed as observed by the radar survey are coincident with regions of the bed with seismic returns indicating drier subglacial sediments. These findings are further supported by five amplitude-verses-offset seismic surveys indicating dilatant till within the ice stream and consolidated sediments within its margins.

  8. The water quality of streams draining a plantation forest on gley soils: the Nant Tanllwyth, Plynlimon mid-Wales

    C. Neal


    Full Text Available The water quality of the Nant Tanllwyth stream in the Plynlimon region of mid-Wales is related to the key hydrobiogeological controls and the effects of conifer harvesting based on an analysis of rain, cloud, stream and groundwater measurements. The results show the normal patterns of stream water quality response to hydrology. Thus, there is a high damping of atmospheric inputs due to storage in a highly heterogeneous soil and groundwater system. Correspondingly, there is a highly dynamic response for components such as calcium, bicarbonate and aluminium. This response links to the relative inputs of acidic and aluminium-bearing soil waters under high flow conditions and base enriched bicarbonate bearing waters from the groundwater areas under baseflow conditions. The introduction of a deep borehole near the main stem of the river opened up a groundwater flow route to the stream and other parts of the catchment. There were two aspects to this. Firstly, it caused a change to the stream water quality, particularly under baseflow conditions, by increasing the concentrations of calcium and magnesium and by reducing the acidity. The monitoring shows that this change has persisted for over eight years and that there is no sign of reversion to pre-borehole times. Secondly, it caused a change in the groundwater level and chemistry at a borehole on the other side of the river. This feature shows that the fracture system is of hydrogeochemical and hydrogeological complexity. The effects of conifer harvesting are remarkable. At the local scale, felling leads to the expected short term increase in nitrate, ammonium and phosphate from the disturbance of the soil and the reduction in uptake into the vegetation. Correspondingly, there is a reduction in sodium and chloride linked to reduced scavenging of atmospheric inputs from cloud water by the vegetation and also due to increased dilution potential due to reductions in transpiration by the trees. However

  9. From soil water to surface water - how the riparian zone controls element transport from a boreal forest to a stream

    Lidman, Fredrik; Boily, Åsa; Laudon, Hjalmar; Köhler, Stephan J.


    Boreal headwaters are often lined by strips of highly organic soils, which are the last terrestrial environment to leave an imprint on discharging groundwater before it enters a stream. Because these riparian soils are so different from the Podzol soils that dominate much of the boreal landscape, they are known to have a major impact on the biogeochemistry of important elements such as C, N, P and Fe and the transfer of these elements from terrestrial to aquatic ecosystems. For most elements, however, the role of the riparian zone has remained unclear, although it should be expected that the mobility of many elements is affected by changes in, for example, pH, redox potential and concentration of organic carbon as they are transported through the riparian zone. Therefore, soil water and groundwater was sampled at different depths along a 22 m hillslope transect in the Krycklan catchment in northern Sweden using soil lysimeters and analysed for a large number of major and trace elements (Al, As, B, Ba, Ca, Cd, Cl, Co, Cr, Cs, Cu, Fe, K, La, Li, Mg, Mn, Na, Ni, Pb, Rb, Se, Si, Sr, Th, Ti, U, V, Zn, Zr) and other parameters such as sulfate and total organic carbon (TOC). The results showed that the concentrations of most investigated elements increased substantially (up to 60 times) as the water flowed from the uphill mineral soils and into the riparian zone, largely as a result of higher TOC concentrations. The stream water concentrations of these elements were typically somewhat lower than in the riparian zone, but still considerably higher than in the uphill mineral soils, which suggests that riparian soils have a decisive impact on the water quality of boreal streams. The degree of enrichment in the riparian zone for different elements could be linked to the affinity for organic matter, indicating that the pattern with strongly elevated concentrations in riparian soils is typical for organophilic substances. One likely explanation is that the solubility of many

  10. The significance and lag-time of deep through flow: an example from a small, ephemeral catchment with contrasting soil types in the Adelaide Hills, South Australia

    J. VanLeeuwen


    Full Text Available The importance of deep soil-regolith through flow in a small (3.4 km2 ephemeral catchment in the Adelaide Hills of South Australia was investigated by detailed hydrochemical analysis of soil water and stream flow during autumn and early winter rains. In this Mediterranean climate with strong summer moisture deficits, several significant rainfalls are required to generate soil through flow and stream flow [in ephemeral streams]. During autumn 2007, a large (127 mm drought-breaking rain occurred in April followed by significant May rains; most of this April and May precipitation occurred prior to the initiation of stream flow in late May. These early events, especially the 127 mm April event, had low stable water isotope values compared with later rains during June and July and average winter precipitation. Thus, this large early autumn rain event with low isotopic values (δ18O, δD provided an excellent natural tracer. During later June and July rainfall events, daily stream and soil water samples were collected and analysed. Results from major and trace elements, water isotopes (δ18O, δD, and dissolved organic carbon analysis clearly demonstrate that a large component of this early April and May rain was stored and later pushed out of deep soil and regolith zones. This pre-event water was identified in the stream as well as identified in deep soil horizons due to its different isotopic signature which contrasted sharply with the June–July event water. Based on this data, the soil-regolith hydrologic system for this catchment has been re-thought. The catchment area consists of about 60% sandy and 40% clayey soils. Regolith flow in the sandy soil system and not the clayey soil system is now thought to dominate the deep subsurface flow in this catchment. The clayey texture contrast soils had rapid response to rain events and saturation excess overland flow. The sandy soils had delayed soil through flow and

  11. Stream Flow Prediction by Remote Sensing and Genetic Programming

    Chang, Ni-Bin


    A genetic programming (GP)-based, nonlinear modeling structure relates soil moisture with synthetic-aperture-radar (SAR) images to present representative soil moisture estimates at the watershed scale. Surface soil moisture measurement is difficult to obtain over a large area due to a variety of soil permeability values and soil textures. Point measurements can be used on a small-scale area, but it is impossible to acquire such information effectively in large-scale watersheds. This model exhibits the capacity to assimilate SAR images and relevant geoenvironmental parameters to measure soil moisture.


    Three soils were examined for the ability to degrade hydrocarbon vapors of benzene, toluene, ethylbenzene, and o-xylene (BTEX). Each of these compounds are major aromatic constituents of gasolines. The soils examined were Rubicon Sand from Traverse City, Michigan, Durant Loam fro...

  13. A stream-gaging network analysis for the 7-Day, 10-year annual low flow in New Hampshire streams

    Flynn, Robert H.


    The 7-day, 10-year (7Q10) low-flow-frequency statistic is a widely used measure of surface-water availability in New Hampshire. Regression equations and basin-characteristic digital data sets were developed to help water-resource managers determine surface-water resources during periods of low flow in New Hampshire streams. These regression equations and data sets were developed to estimate streamflow statistics for the annual and seasonal low-flow-frequency, and period-of-record and seasonal period-of-record flow durations. generalized-least-squares (GLS) regression methods were used to develop the annual 7Q10 low-flow-frequency regression equation from 60 continuous-record stream-gaging stations in New Hampshire and in neighboring States. In the regression equation, the dependent variables were the annual 7Q10 flows at the 60 stream-gaging stations. The independent (or predictor) variables were objectively selected characteristics of the drainage basins that contribute flow to those stations. In contrast to ordinary-least-squares (OLS) regression analysis, GLS-developed estimating equations account for differences in length of record and spatial correlations among the flow-frequency statistics at the various stations. A total of 93 measurable drainage-basin characteristics were candidate independent variables. On the basis of several statistical parameters that were used to evaluate which combination of basin characteristics contribute the most to the predictive power of the equations, three drainage-basin characteristics were determined to be statistically significant predictors of the annual 7Q10: (1) total drainage area, (2) mean summer stream-gaging station precipitation from 1961 to 90, and (3) average mean annual basinwide temperature from 1961 to 1990. To evaluate the effectiveness of the stream-gaging network in providing regional streamflow data for the annual 7Q10, the computer program GLSNET (generalized-least-squares NETwork) was used to analyze the

  14. Impact of Climate Change Adaptation Options on Stream Flow

    Mishra, Ashok; Bhave, Ajay; Raghuwanshi, Narendra


    Climate change, now, is taken as a reality with distressing effects on natural resources. It is an established fact that the negative impacts of climate change on freshwater will be greater with increased precipitation variability and seasonal runoff shifts on water supply and consequent impacts on water quantity and quality. Therefore, this sector necessitates identification of possible long term adaptation to changing climate and their impacts on regional water availability and demand. We assessed three stakeholder-identified adaptation options namely- construction of traditional ponds (TP), construction of check dams (CD) and increased forest cover (IFC) in Kangsabati reservoir catchment and command area, in India using the Water Evaluation And Planning (WEAP) model. Four high resolution ( 25km) regional climate model outputs and their ensemble for the period 2021-2050 provide a range of future climate (2021-2050) scenarios to force the WEAP model. Calibrated (1991-2000) and validated (2001-2010) WEAP model with reasonable NSE, R2 and PBIAS statistics has been used to test the effects of identified adaptation options on unmet demand of water, runoff generation and peak stream flow. Applying one traditional ponds for every 1 km2 area reduced unmet irrigation water demand by 4.5 x 109 m3 with reduced peak water demand from 0.78 x 109 m3 to 0.7 x 109 m3 compared to non-adaptation scenario. Increasing forest cover reduces runoff by 1000 times more than check dams and reduces monsoon season peak runoff rate as well. IFC demonstrates greater ability to meet the adaptation requirement by reducing high flows by upto 8 m3/s during monsoon season and increasing reservoir inflow by upto 0.5 m3/s during the lean season. While there is uncertainty in the magnitude of change of streamflow due to the effect of adaptation options, there is greater certainty in the sign of change. Results indicate that check dams and increasing forest cover as adaptation strategies have a

  15. Ecoenzymatic Stoichiometry of Stream Sediments with Comparison to Terrestrial Soils

    In this study, we extend the development of ecoenzymatic stoichiometry to the surface sediments of stream ecosystems using data collected in a nationwide survey. The data set is larger and more comprehensive than those used in our previous studies. The data include the first broa...

  16. Ecoenzymatic Stoichiometry of Stream Sediments with Comparison to Terrestrial Soils

    In this study, we extend the development of ecoenzymatic stoichiometry to the surface sediments of stream ecosystems using data collected in a nationwide survey. The data set is larger and more comprehensive than those used in our previous studies. The data include the first broa...

  17. Controls on old and new water contributions to stream flow at some nested catchments in Vermont, USA

    Shanley, J.B.; Kendall, C.; Smith, T.E.; Wolock, D.M.; McDonnell, Jeffery J.


    Factors controlling the partitioning of old and new water contributions to stream flow were investigated for three events in four catchments (three of which were nested) at Sleepers River Research Watershed in Danville, Vermont. In the 1993 snowmelt period, two-component isotopic hydrograph separations showed that new water (meltwater) inputs to the stream ranged widely from 41 to 74%, and increased with catchment size (41 to 11 125 ha) (with one exception) and with open land cover (0-73%). Peak dissolved organic carbon concentrations and relative alkalinity dilution in stream water ranked in the same order among catchments as the new water fractions, suggesting that new water followed shallow flow paths. During the 1994 snowmelt, despite similar timing and magnitude of melt inputs, the new-water contribution to stream flow ranged only from 30 to 36% in the four catchments. We conclude that the uncommonly high and variable new water fractions in streamwater during the 1993 melt were caused by direct runoff of meltwater over frozen ground, which was prevalent in open land areas during the 1993 winter. In a high-intensity summer rainstorm in 1993, new water fractions were smaller relative to the 1993 snowmelt, ranging from 28 to 46%, but they ranked in the identical catchment order. Reconciliation of the contrasting patterns of new-old water partitioning in the three events appears to require an explanation that invokes multiple processes and effects, including: 1 topographically controlled increase in surface-saturated area with increasing catchment size; 2 direct runoff over frozen ground; 3 low infiltration in agriculturally compacted soils; 4 differences in soil transmissivity, which may be more relevant under dry antecedent conditions. These data highlight some of the difficulties faced by catchment hydrologists in formulating a theory of runoff generation at varying basin scales. Copyright ?? 2002 John Wiley and Sons, Ltd.

  18. Macroinvertebrate survival during cessation of flow and streambed drying in a lowland stream

    Verdonschot, R.C.M.; Oosten-Siedlecka, van A.M.; Braak, ter C.J.F.; Verdonschot, P.F.M.


    1.The number of perennial low-order lowland streams likely to experience intermittent flow is predicted to increase in north-western Europe. To understand the effects of such a change on macroinvertebrates, a field experiment was carried out in a currently perennial sandy lowland stream. 2.Using a b

  19. Technical Manual for the Geospatial Stream Flow Model (GeoSFM)

    Asante, Kwabena O.; Artan, Guleid A.; Pervez, Md Shahriar; Bandaragoda, Christina; Verdin, James P.


    The monitoring of wide-area hydrologic events requires the use of geospatial and time series data available in near-real time. These data sets must be manipulated into information products that speak to the location and magnitude of the event. Scientists at the U.S. Geological Survey Earth Resources Observation and Science (USGS EROS) Center have implemented a hydrologic modeling system which consists of an operational data processing system and the Geospatial Stream Flow Model (GeoSFM). The data processing system generates daily forcing evapotranspiration and precipitation data from various remotely sensed and ground-based data sources. To allow for rapid implementation in data scarce environments, widely available terrain, soil, and land cover data sets are used for model setup and initial parameter estimation. GeoSFM performs geospatial preprocessing and postprocessing tasks as well as hydrologic modeling tasks within an ArcView GIS environment. The integration of GIS routines and time series processing routines is achieved seamlessly through the use of dynamically linked libraries (DLLs) embedded within Avenue scripts. GeoSFM is run operationally to identify and map wide-area streamflow anomalies. Daily model results including daily streamflow and soil water maps are disseminated through Internet map servers, flood hazard bulletins and other media.

  20. Performance of TCP-friendly streaming sessions in the presence of heavy-tailed elastic flows

    Bekker, R.; Borst, S.C.; Núñez Queija, R.


    We consider a fixed number of streaming sessions which share a bottleneck link with a dynamic population of elastic flows. Motivated by extensive measurement studies, we assume that the sizes of the elastic flows exhibit heavy-tailed characteristics. The elastic flows are TCP-controlled, while the t

  1. Subglacial water flow inferred from stream measurements at South Cascade Glacier, Washington, USA

    Fountain, A.G.


    Comparisons of water discharge and cation load in each of the two main streams indicate that subglacial hydraulic processes differ between drainage basins. One stream drains from a conduit that is isolated in its lower reach from the surrounding subglacial region and receives water routed englacially from the surface. The upper reach of the conduit also receives water rounted englacially from the surface as well as from a distributed subglacial flow system. The other main stream drains from a conduit coupled to a debris layer beneath the glacier. Observations of the layer in natural ice tunnels indicate that the water may flow within a thin layer of debris. A one-dimensional model of flow through the debris layer can explain both the base-flow and diurnal variations of the second main stream. -from Author

  2. Flow Data for Solute Transport Modeling from Tracer Experiments in a Stream Not Continuously Gaining Water

    Bencala, K. E.; Kimball, B. A.; Gooseff, M. N.


    In-stream tracer experiments are a well-established method for determining flow data to be incorporated in solute transport modeling. For a gaining stream, this method is implemented to provide spatial flow data at scales of minutes and tens of meters without physical disturbance to the flow of water, the streambed, or biota. Of importance for solute transport modeling, solute inflow loading along the stream can be estimated with this spatial data. The tracer information can also be interpreted to characterize hyporheic exchange time-scales for a stream with hyporheic exchange flowpaths (HEFs) that are short relative to the distance over which the stream gains water. The interpretation of tracer data becomes uncertain for a stream that is not gaining water continuously over intended study reach. We demonstrate, with straight-forward mass-balances, uncertainties for solute loading which arise in the analysis of streams locally losing water while predominantly gaining water (and solutes) over a larger scale. With field data from Mineral Creek (Silverton, Colorado) we illustrate the further uncertainty distinguishing HEFs from (locally) losing segments of the stream. Comparison of bromide tracer with ambient sulfate concentrations suggests that subsurface inflows and outflows, concurrent with likely HEFs, occur in a hydrogeochemical setting of multiple, dispersed and mixed, sources of water along a 64 m sub-reach of the predominately gaining, but locally losing, stream. To compute stream-reach mass-balances (the simplest of water quality models) there is a need to quantitatively define the character and source of contaminants entering streams from ground-water pathways, as well as the potential for changes in water chemistry and contaminant concentrations along flow paths crossing the sediment-water interface. Identification of inflow solute mass requires quantifying water gain, loss, and hyporheic exchange in addition to concentration.

  3. Speciation and equilibrium relations of soluble aluminum in a headwater stream at base flow and during rain events

    Burns, Douglas A.


    In the Shenandoah National Park, Virginia, the short-term dynamics of soluble aluminum in stream water sampled during rain events differed significantly from stream water sampled during base flow conditions. Three fractions of dissolved aluminum were measured. The inorganic monomeric fraction made up approximately two thirds of the total reactive aluminum at base flow, followed by the acid-soluble and organic monomeric fractions, respectively. Equilibrium modeling showed that hydroxide complexes were the most abundant form of inorganic monomeric aluminum followed by fluoride, free aluminum ion, and sulfate. The activity of inorganic monomeric aluminum at base flow appears to be in equilibrium with an Al(OH)3 phase with solubility intermediate between microcrystalline gibbsite and natural gibbsite. During two rain events, the concentration of all three aluminum fractions increased significantly. The primary cause of the transient increase in the Al(OH)3 saturation index appears to have been the neutralization of excess H+ added by soil water through reaction with stream water HCO3- at a more rapid rate than excess inorganic monomeric aluminum could be removed from solution by hydroxide mineral precipitation. -from Author

  4. Development of the Hydroecological Integrity Assessment Process for Determining Environmental Flows for New Jersey Streams

    Kennen, Jonathan G.; Henriksen, James A.; Nieswand, Steven P.


    The natural flow regime paradigm and parallel stream ecological concepts and theories have established the benefits of maintaining or restoring the full range of natural hydrologic variation for physiochemical processes, biodiversity, and the evolutionary potential of aquatic and riparian communities. A synthesis of recent advances in hydroecological research coupled with stream classification has resulted in a new process to determine environmental flows and assess hydrologic alteration. This process has national and international applicability. It allows classification of streams into hydrologic stream classes and identification of a set of non-redundant and ecologically relevant hydrologic indices for 10 critical sub-components of flow. Three computer programs have been developed for implementing the Hydroecological Integrity Assessment Process (HIP): (1) the Hydrologic Indices Tool (HIT), which calculates 171 ecologically relevant hydrologic indices on the basis of daily-flow and peak-flow stream-gage data; (2) the New Jersey Hydrologic Assessment Tool (NJHAT), which can be used to establish a hydrologic baseline period, provide options for setting baseline environmental-flow standards, and compare past and proposed streamflow alterations; and (3) the New Jersey Stream Classification Tool (NJSCT), designed for placing unclassified streams into pre-defined stream classes. Biological and multivariate response models including principal-component, cluster, and discriminant-function analyses aided in the development of software and implementation of the HIP for New Jersey. A pilot effort is currently underway by the New Jersey Department of Environmental Protection in which the HIP is being used to evaluate the effects of past and proposed surface-water use, ground-water extraction, and land-use changes on stream ecosystems while determining the most effective way to integrate the process into ongoing regulatory programs. Ultimately, this scientifically defensible

  5. Testing and comparison of four ionic tracers to measure stream flow loss by multiple tracer injection

    Zellweger, G.W.


    An injectate containing lithium, sodium, chloride and bromide was added continuously at five sites along a 507 m study reach of St Kevin Gulch, Lake County, Colorado to determine which sections of the stream were losing water to the stream bed and to ascertain how well the four tracers performed. The acidity of the stream (pH 3.6) made it possible for lithium and sodium, which are normally absorbed by ion exchange with stream bed sediment, to be used as conservative tracers. Net flow losses as low as 0.81 s-1, or 8% of flow, were calculated between measuring sites. By comparing the results of simultaneous injection it was determined whether subsections of the study reach were influent or effluent. Evaluation of tracer concentrations along 116 m of stream indicated that all four tracers behaved conservatively. Discharges measured by Parshall flumes were 4-18% greater than discharges measured by tracer dilution. -from Author

  6. Passive microfluidic control of two merging streams by capillarity and relative flow resistance.

    Kim, Sung-Jin; Lim, Yong Taik; Yang, Haesik; Shin, Yong Beom; Kim, Kyuwon; Lee, Dae-Sik; Park, Se Ho; Kim, Youn Tae


    In the progress of microfluidic devices, a simple and precise control of multiple streams has been essential for complex microfluidic networks. Consequently, microfluidic devices, which have a simple structure, typically use external energy sources to control the multiple streams. Here, we propose a pure passive scheme that uses capillarity without using external force or external regulation to control the merging of two streams and even to regulate their volumetric flow rate (VFR). We accomplish this process by controlling the geometry of two inlets and a junction, and by regulating the hydrophilicity of a substrate. Additionally, we use the relative flow resistance to control the VFR ratio of the merged two streams. Our results will significantly simplify the control of multiple streams without sacrificing precision.

  7. Flow Durations, Low-Flow Frequencies, and Monthly Median Flows for Selected Streams in Connecticut through 2005

    Ahearn, Elizabeth A.


    Flow durations, low-flow frequencies, and monthly median streamflows were computed for 91 continuous-record, streamflow-gaging stations in Connecticut with 10 or more years of record. Flow durations include the 99-, 98-, 97-, 95-, 90-, 85-, 80-, 75-, 70-, 60-, 50-, 40-, 30-, 25-, 20-, 10-, 5-, and 1-percent exceedances. Low-flow frequencies include the 7-day, 10-year (7Q10) low flow; 7-day, 2-year (7Q2) low flow; and 30-day, 2-year (30Q2) low flow. Streamflow estimates were computed for each station using data for the period of record through water year 2005. Estimates of low-flow statistics for 7 short-term (operated between 3 and 10 years) streamflow-gaging stations and 31 partial-record sites were computed. Low-flow estimates were made on the basis of the relation between base flows at a short-term station or partial-record site and concurrent daily mean streamflows at a nearby index station. The relation is defined by the Maintenance of Variance Extension, type 3 (MOVE.3) method. Several short-term stations and partial-record sites had poorly defined relations with nearby index stations; therefore, no low-flow statistics were derived for these sites. The estimated low-flow statistics for the short-term stations and partial-record sites include the 99-, 98-, 97-, 95-, 90-, and 85-percent flow durations; the 7-day, 10-year (7Q10) low flow; 7-day, 2-year (7Q2) low flow; and 30-day, 2-year (30Q2) low-flow frequencies; and the August median flow. Descriptive information on location and record length, measured basin characteristics, index stations correlated to the short-term station and partial-record sites, and estimated flow statistics are provided in this report for each station. Streamflow estimates from this study are stored on USGS's World Wide Web application 'StreamStats' (

  8. Selective particle and cell capture in a continuous flow using micro-vortex acoustic streaming.

    Collins, David J; Khoo, Bee Luan; Ma, Zhichao; Winkler, Andreas; Weser, Robert; Schmidt, Hagen; Han, Jongyoon; Ai, Ye


    Acoustic streaming has emerged as a promising technique for refined microscale manipulation, where strong rotational flow can give rise to particle and cell capture. In contrast to hydrodynamically generated vortices, acoustic streaming is rapidly tunable, highly scalable and requires no external pressure source. Though streaming is typically ignored or minimized in most acoustofluidic systems that utilize other acoustofluidic effects, we maximize the effect of acoustic streaming in a continuous flow using a high-frequency (381 MHz), narrow-beam focused surface acoustic wave. This results in rapid fluid streaming, with velocities orders of magnitude greater than that of the lateral flow, to generate fluid vortices that extend the entire width of a 400 μm wide microfluidic channel. We characterize the forces relevant for vortex formation in a combined streaming/lateral flow system, and use these acoustic streaming vortices to selectively capture 2 μm from a mixed suspension with 1 μm particles and human breast adenocarcinoma cells (MDA-231) from red blood cells.

  9. Solute transport processes in flow-event-driven stream-aquifer interaction

    Xie, Yueqing; Cook, Peter G.; Simmons, Craig T.


    The interaction between streams and groundwater controls key features of the stream hydrograph and chemograph. Since surface runoff is usually less saline than groundwater, flow events are usually accompanied by declines in stream salinity. In this paper, we use numerical modelling to show that, at any particular monitoring location: (i) the increase in stream stage associated with a flow event will precede the decrease in solute concentration (arrival time lag for solutes); and (ii) the decrease in stream stage following the flow peak will usually precede the subsequent return (increase) in solute concentration (return time lag). Both arrival time lag and return time lag increase with increasing wave duration. However, arrival time lag decreases with increasing wave amplitude, whereas return time lag increases. Furthermore, while arrival time lag is most sensitive to parameters that control river velocity (channel roughness and stream slope), return time lag is most sensitive to groundwater parameters (aquifer hydraulic conductivity, recharge rate, and dispersitivity). Additionally, the absolute magnitude of the decrease in river concentration is sensitive to both river and groundwater parameters. Our simulations also show that in-stream mixing is dominated by wave propagation and bank storage processes, and in-stream dispersion has a relatively minor effect on solute concentrations. This has important implications for spreading of contaminants released to streams. Our work also demonstrates that a high contribution of pre-event water (or groundwater) within the flow hydrograph can be caused by the combination of in-stream and bank storage exchange processes, and does not require transport of pre-event water through the catchment.

  10. Relation of streams, lakes, and wetlands to groundwater flow systems

    Winter, Thomas C.

    Surface-water bodies are integral parts of groundwater flow systems. Groundwater interacts with surface water in nearly all landscapes, ranging from small streams, lakes, and wetlands in headwater areas to major river valleys and seacoasts. Although it generally is assumed that topographically high areas are groundwater recharge areas and topographically low areas are groundwater discharge areas, this is true primarily for regional flow systems. The superposition of local flow systems associated with surface-water bodies on this regional framework results in complex interactions between groundwater and surface water in all landscapes, regardless of regional topographic position. Hydrologic processes associated with the surface-water bodies themselves, such as seasonally high surface-water levels and evaporation and transpiration of groundwater from around the perimeter of surface-water bodies, are a major cause of the complex and seasonally dynamic groundwater flow fields associated with surface water. These processes have been documented at research sites in glacial, dune, coastal, mantled karst, and riverine terrains. Résumé Les eaux de surface sont parties intégrantes des systèmes aquifères. Les eaux souterraines interagissent avec les eaux de surface dans presque tous les types d'environnements, depuis les petits ruisseaux, les lacs et les zones humides jusqu'aux bassins versants des vallées des grands fleuves et aux lignes de côte. Il est en général admis que les zones topographiquement hautes sont des lieux de recharge des aquifères et les zones basses des lieux de décharge, ce qui est le cas des grands systèmes aquifères régionaux. La superposition de systèmes locaux, associés à des eaux de surface, à l'organisation régionale d'écoulements souterrains résulte d'interactions complexes entre les eaux souterraines et les eaux de surface dans tous les environnements, quelle que soit la situation topographique régionale. Les processus

  11. Pool-type fishways: two different morpho-ecological cyprinid species facing plunging and streaming flows.

    Branco, Paulo; Santos, José M; Katopodis, Christos; Pinheiro, António; Ferreira, Maria T


    Fish are particularly sensitive to connectivity loss as their ability to reach spawning grounds is seriously affected. The most common way to circumvent a barrier to longitudinal connectivity, and to mitigate its impacts, is to implement a fish passage device. However, these structures are often non-effective for species with different morphological and ecological characteristics so there is a need to determine optimum dimensioning values and hydraulic parameters. The aim of this work is to study the behaviour and performance of two species with different ecological characteristics (Iberian barbel Luciobarbus bocagei-bottom oriented, and Iberian chub Squalius pyrenaicus-water column) in a full-scale experimental pool-type fishway that offers two different flow regimes-plunging and streaming. Results showed that both species passed through the surface notch more readily during streaming flow than during plunging flow. The surface oriented species used the surface notch more readily in streaming flow, and both species were more successful in moving upstream in streaming flow than in plunging flow. Streaming flow enhances upstream movement of both species, and seems the most suitable for fishways in river systems where a wide range of fish morpho-ecological traits are found.

  12. Predicting spatial distribution of postfire debris flows and potential consequences for native trout in headwater streams

    Sedell, Edwin R; Gresswell, Bob; McMahon, Thomas E.


    Habitat fragmentation and degradation and invasion of nonnative species have restricted the distribution of native trout. Many trout populations are limited to headwater streams where negative effects of predicted climate change, including reduced stream flow and increased risk of catastrophic fires, may further jeopardize their persistence. Headwater streams in steep terrain are especially susceptible to disturbance associated with postfire debris flows, which have led to local extirpation of trout populations in some systems. We conducted a reach-scale spatial analysis of debris-flow risk among 11 high-elevation watersheds of the Colorado Rocky Mountains occupied by isolated populations of Colorado River Cutthroat Trout (Oncorhynchus clarkii pleuriticus). Stream reaches at high risk of disturbance by postfire debris flow were identified with the aid of a qualitative model based on 4 primary initiating and transport factors (hillslope gradient, flow accumulation pathways, channel gradient, and valley confinement). This model was coupled with a spatially continuous survey of trout distributions in these stream networks to assess the predicted extent of trout population disturbances related to debris flows. In the study systems, debris-flow potential was highest in the lower and middle reaches of most watersheds. Colorado River Cutthroat Trout occurred in areas of high postfire debris-flow risk, but they were never restricted to those areas. Postfire debris flows could extirpate trout from local reaches in these watersheds, but trout populations occupy refugia that should allow recolonization of interconnected, downstream reaches. Specific results of our study may not be universally applicable, but our risk assessment approach can be applied to assess postfire debris-flow risk for stream reaches in other watersheds.

  13. Altered stream-flow regimes and invasive plant species: The Tamarix case

    Stromberg, J.C.; Lite, S.J.; Marler, R.; Paradzick, C.; Shafroth, P.B.; Shorrock, D.; White, J.M.; White, M.S.


    Aim: To test the hypothesis that anthropogenic alteration of stream-flow regimes is a key driver of compositional shifts from native to introduced riparian plant species. Location: The arid south-western United States; 24 river reaches in the Gila and Lower Colorado drainage basins of Arizona. Methods: We compared the abundance of three dominant woody riparian taxa (native Populus fremontii and Salix gooddingii, and introduced Tamarix) between river reaches that varied in stream-flow permanence (perennial vs. intermittent), presence or absence of an upstream flow-regulating dam, and presence or absence of municipal effluent as a stream water source. Results: Populus and Salix were the dominant pioneer trees along the reaches with perennial flow and a natural flood regime. In contrast, Tamarix had high abundance (patch area and basal area) along reaches with intermittent stream flows (caused by natural and cultural factors), as well as those with dam-regulated flows. Main conclusions: Stream-flow regimes are strong determinants of riparian vegetation structure, and hydrological alterations can drive dominance shifts to introduced species that have an adaptive suite of traits. Deep alluvial groundwater on intermittent rivers favours the deep-rooted, stress-adapted Tamarix over the shallower-rooted and more competitive Populus and Salix. On flow-regulated rivers, shifts in flood timing favour the reproductively opportunistic Tamarix over Populus and Salix, both of which have narrow germination windows. The prevailing hydrological conditions thus favour a new dominant pioneer species in the riparian corridors of the American Southwest. These results reaffirm the importance of reinstating stream-flow regimes (inclusive of groundwater flows) for re-establishing the native pioneer trees as the dominant forest type. ?? 2007 The Authors Journal compilation ?? 2007 Blackwell Publishing Ltd.

  14. Hyporheic flow pattern based on the coupling of regional and stream scales: Case of Krycklan Catchment area

    Mojarrad, Morteza; Wörman, Anders; Riml, Joakim


    Water resources intense development within the past century has had an enormous impact on hydrological systems especially on rivers and groundwater resources. A river basin is a flow system involving the interaction between surface water and groundwater. This interaction occurs in terrestrial and coastal zone and even in arid and semi-arid areas, where surface water overlie on a permeable sediment. A key zone for the interaction between surface water and groundwater is the hyporheic zone, which forms by stream water that in- and exfiltrating in the permeable sediments surrounding the river corridor. Groundwater and hyporheic flows arise due to different range of topographical scales and their relative importance is investigated in this study. Krycklan is a well-monitored research catchment in which the data collection for more than 90 years has comprised hydrology, biochemistry, and aquatic ecology. The catchment is located in a boreal area of northern Sweden. The head-water streams begin in mountainous area and fall to the Baltic Sea near the city of Umea. In this paper, COMSOL Multi-physics simulation software has been used to model the subsurface flow of the whole Krycklan catchment in order to reach a comprehensive understanding of large-scale groundwater circulation and its impact of the stream hyporheic flows. The model statement is based on the 3D Laplace equation, which has been applied independently on two ranges of topographical scales to obtain a superimposed solution. Steady state simulation has been done based on the simplified assumption of constant boundary conditions of the groundwater surface and otherwise non-flow boundaries. The hydraulic head of the groundwater surface was taken as the topography, which apply as an approximation in wet climate with shallow soil layers. The results demonstrated how the ratio of the topographical amplitudes on different scales affect the size (depth) and fragmentation of the hyporheic zone. "Fragmentation" was

  15. Ambient groundwater flow diminishes nitrate processing in the hyporheic zone of streams

    Azizian, Morvarid; Boano, Fulvio; Cook, Perran L. M.; Detwiler, Russell L.; Rippy, Megan A.; Grant, Stanley B.


    Modeling and experimental studies demonstrate that ambient groundwater reduces hyporheic exchange, but the implications of this observation for stream N-cycling is not yet clear. Here we utilize a simple process-based model (the Pumping and Streamline Segregation or PASS model) to evaluate N-cycling over two scales of hyporheic exchange (fluvial ripples and riffle-pool sequences), ten ambient groundwater and stream flow scenarios (five gaining and losing conditions and two stream discharges), and three biogeochemical settings (identified based on a principal component analysis of previously published measurements in streams throughout the United States). Model-data comparisons indicate that our model provides realistic estimates for direct denitrification of stream nitrate, but overpredicts nitrification and coupled nitrification-denitrification. Riffle-pool sequences are responsible for most of the N-processing, despite the fact that fluvial ripples generate 3-11 times more hyporheic exchange flux. Across all scenarios, hyporheic exchange flux and the Damköhler Number emerge as primary controls on stream N-cycling; the former regulates trafficking of nutrients and oxygen across the sediment-water interface, while the latter quantifies the relative rates of organic carbon mineralization and advective transport in streambed sediments. Vertical groundwater flux modulates both of these master variables in ways that tend to diminish stream N-cycling. Thus, anthropogenic perturbations of ambient groundwater flows (e.g., by urbanization, agricultural activities, groundwater mining, and/or climate change) may compromise some of the key ecosystem services provided by streams.

  16. Flow directionality, mountain barriers and functional traits determine diatom metacommunity structuring of high mountain streams.

    Dong, Xiaoyu; Li, Bin; He, Fengzhi; Gu, Yuan; Sun, Meiqin; Zhang, Haomiao; Tan, Lu; Xiao, Wen; Liu, Shuoran; Cai, Qinghua


    Stream metacommunities are structured by a combination of local (environmental filtering) and regional (dispersal) processes. The unique characters of high mountain streams could potentially determine metacommunity structuring, which is currently poorly understood. Aiming at understanding how these characters influenced metacommunity structuring, we explored the relative importance of local environmental conditions and various dispersal processes, including through geographical (overland), topographical (across mountain barriers) and network (along flow direction) pathways in shaping benthic diatom communities. From a trait perspective, diatoms were categorized into high-profile, low-profile and motile guild to examine the roles of functional traits. Our results indicated that both environmental filtering and dispersal processes influenced metacommunity structuring, with dispersal contributing more than environmental processes. Among the three pathways, stream corridors were primary pathway. Deconstructive analysis suggested different responses to environmental and spatial factors for each of three ecological guilds. However, regardless of traits, dispersal among streams was limited by mountain barriers, while dispersal along stream was promoted by rushing flow in high mountain stream. Our results highlighted that directional processes had prevailing effects on metacommunity structuring in high mountain streams. Flow directionality, mountain barriers and ecological guilds contributed to a better understanding of the roles that mountains played in structuring metacommunity.

  17. Effects of flow scarcity on leaf-litter processing under oceanic climate conditions in calcareous streams.

    Martínez, Aingeru; Pérez, Javier; Molinero, Jon; Sagarduy, Mikel; Pozo, Jesús


    Although temporary streams represent a high proportion of the total number and length of running waters, historically the study of intermittent streams has received less attention than that of perennial ones. The goal of the present study was to assess the effects of flow cessation on litter decomposition in calcareous streams under oceanic climate conditions. For this, leaf litter of alder was incubated in four streams (S1, S2, S3 and S4) with different flow regimes (S3 and S4 with zero-flow periods) from northern Spain. To distinguish the relative importance and contribution of decomposers and detritivores, fine- and coarse-mesh litter bags were used. We determined processing rates, leaf-C, -N and -P concentrations, invertebrate colonization in coarse bags and benthic invertebrates. Decomposition rates in fine bags were similar among streams. In coarse bags, only one of the intermittent streams, S4, showed a lower rate than that in the other ones as a consequence of lower invertebrate colonization. The material incubated in fine bags presented higher leaf-N and -P concentrations than those in the coarse ones, except in S4, pointing out that the decomposition in this stream was driven mainly by microorganisms. Benthic macroinvertebrate and shredder density and biomass were lower in intermittent streams than those in perennial ones. However, the bags in S3 presented a greater amount of total macroinvertebrates and shredders comparing with the benthos. The most suitable explanation is that the fauna find a food substrate in bags less affected by calcite precipitation, which is common in the streambed at this site. Decomposition rate in coarse bags was positively related to associated shredder biomass. Thus, droughts in streams under oceanic climate conditions affect mainly the macroinvertebrate detritivore activity, although macroinvertebrates may show distinct behavior imposed by the physicochemical properties of water, mainly travertine precipitation, which can

  18. Dating base flow in streams using dissolved gases and diurnal temperature changes

    Sanford, Ward E.; Casile, Gerolamo C.; Haase, Karl B.


    A method is presented for using dissolved CFCs or SF6 to estimate the apparent age of stream base flow by indirectly estimating the mean concentration of the tracer in the inflowing groundwater. The mean value is estimated simultaneously with the mean residence times of the gas and water in the stream by sampling the stream for one or both age tracers, along with dissolved nitrogen and argon at a single location over a period of approximately 12–14 h. The data are fitted to an equation representing the temporal in-stream gas exchange as it responds to the diurnal temperature fluctuation. The efficacy of the method is demonstrated by collecting and analyzing samples at six different stream locations across parts of northern Virginia, USA. The studied streams drain watersheds with areas of between 2 and 122 km2 during periods when the diurnal stream temperature ranged between 2 and 5°C. The method has the advantage of estimating the mean groundwater residence time of discharge from the watershed to the stream without the need for the collection of groundwater infiltrating to streambeds or local groundwater sampled from shallow observation wells near the stream.

  19. Rethinking hyporheic flow and transient storage to advance understanding of stream-catchment connections

    Bencala, K.E.; Gooseff, M.N.; Kimball, B.A.


    Although surface water and groundwater are increasingly referred to as one resource, there remain environmental and ecosystem needs to study the 10 m to 1 km reach scale as one hydrologic system. Streams gain and lose water over a range of spatial and temporal scales. Large spatial scales (kilometers) have traditionally been recognized and studied as river-aquifer connections. Over the last 25 years hyporheic exchange flows (1-10 m) have been studied extensively. Often a transient storage model has been used to quantify the physical solute transport setting in which biogeochemical processes occur. At the longer 10 m to 1 km scale of stream reaches it is now clear that streams which gain water overall can coincidentally lose water to the subsurface. At this scale, the amounts of water transferred are not necessarily significant but the exchanges can, however, influence solute transport. The interpretation of seemingly straightforward questions about water, contaminant, and nutrient fluxes into and along a stream can be confounded by flow losses which are too small to be apparent in stream gauging and along flow paths too long to be detected in tracer experiments. We suggest basic hydrologic approaches, e.g., measurement of flow along the channel, surface and subsurface solute sampling, and routine measurements of the water table that, in our opinion, can be used to extend simple exchange concepts from the hyporheic exchange scale to a scale of stream-catchment connection. Copyright 2011 by the American Geophysical Union.

  20. 78 FR 65306 - Best Practices for Continuous Monitoring of Temperature and Flow in Wadeable Streams


    ... AGENCY Best Practices for Continuous Monitoring of Temperature and Flow in Wadeable Streams AGENCY...: EPA is announcing a 30-day public comment period for the draft document titled, ``Best Practices for... Development. The report describes best practices for the deployment of continuous temperature and flow sensors...

  1. Using Remote Sensing, Geomorphology, and Soils to Map Episodic Streams in Drylands

    Thibodeaux-Yost, S. N. S.


    Millions of acres of public land in the California deserts are currently being evaluated and permitted for the construction of large-scale renewable energy projects. The absence of a standard method for identifying episodic streams in arid and semi-arid (dryland) regions is a source of conflict between project developers and the government agencies responsible for conserving natural resources and permitting renewable energy projects. There is a need for a consistent, efficient, and cost-effective dryland stream delineation protocol that accurately reflects the extent and distribution of active watercourses. This thesis evaluates the stream delineation method and results used by the developer for the proposed Ridgecrest Solar Power Project on the El Paso Fan, Ridgecrest, Kern County, California. This evaluation is then compared and contrasted with results achieved using remote sensing, geomorphology, soils, and GIS analysis to identify stream presence on the site. This study's results identified 105 acres of watercourse, a value 10 times greater than that originally identified by the project developer. In addition, the applied methods provide an ecohydrologic base map to better inform project siting and potential project impact mitigation opportunities. This study concludes that remote sensing, geomorphology, and dryland soils can be used to accurately and efficiently identify episodic stream activity and the extent of watercourses in dryland environments.

  2. Stream Biofilm Responses to Flow Intermittency: From Cells to Ecosystems

    Sabater, Sergi; Timoner, Xisca; Borrego, Carles; Acuña, Vicenç


    Temporary streams are characterized by the alternation of dry and wet hydrological phases, creating both a harsh environment for the biota as well as a high diversity of opportunities for adaptation. These systems are mainly microbial-based during several of these hydrological phases, and those growing on all solid substrata (biofilms) accordingly change their physical structure and community composition. Biofilms experience large decreases in cell densities and biomass, both of bacteria and ...

  3. Groundwater flow and mixing in a wetland–stream system

    Karan, Sachin; Engesgaard, Peter Knudegaard; Zibar, Majken Caroline Looms;


    We combined electrical resistivity tomography (ERT) on land and in a stream with zone-based hydraulic conductivities (from multi-level slug testing) to investigate the local geological heterogeneity of the deposits in a wetland–stream system. The detailed geology was incorporated into a numerical....... The presented approach of integrating such methods in groundwater–surface water exchange studies, proved efficient to obtain information of the controlling factors....... steady-state groundwater model that was calibrated against average head observations. The model results were tested against groundwater fluxes determined from streambed temperature measurements. Discharge varied up to one order of magnitude across the stream and the model was successful in capturing...... this variability. Water quality analyses from multi-level sampling underneath the streambed and in the wetland showed a stratification in groundwater composition with an aerobic shallow zone with oxygen and nitrate (top ∼3 m) overlying a reduced, anoxic zone. While NO3- concentrations up to 58 mg L−1 were found...

  4. Stream flow - its estimation, uncertainty and interaction with groundwater and floodplains

    Poulsen, Jane Bang

    regimes were predicted by the flow model with shifting primary overbank flow and zones of flow confluence. These dynamic flow patterns were found to correlate with the spatial deposition of total phosphorus (11.4 g m-2), organic matter (0.65 kg m-2) and sediment (4.72 kg m-2), and zones of major total......, floodplain hydraulics and sedimentation patterns has been investigated along a restored channel section of Odense stream, Denmark. Collected samples of deposited sediment, organic matter and phosphorus on the floodplain were compared with results from a 2D dynamic flow model. Three stage dependent flow...

  5. Analog modeling of transient moisture flow in unsaturated soil

    Wind, G.P.


    Hydraulic and electronic analog models are developed for the simulation of moisture flow and accumulation in unsaturated soil. The analog models are compared with numerical models and checked with field observations. Application of soil physical knowledge on a soil technological problem by means of

  6. Measurements of the streaming potential of clay soils from tropical and subtropical regions using self-made apparatus.

    Li, Zhong-Yi; Li, Jiu-Yu; Liu, Yuan; Xu, Ren-Kou


    The streaming potential has been wildly used in charged parallel plates, capillaries, and porous media. However, there have been few studies involving the ζ potential of clay soils based on streaming potential measurements. A laboratory apparatus was developed in this study to measure the streaming potential (ΔE) of bulk clay soils' coupling coefficient (C) and cell resistance (R) of saturated granular soil samples. Excellent linearity of ΔE versus liquid pressure (ΔP) ensured the validity of measurements. The obtained parameters of C and R can be used to calculate the ζ potential of bulk soils. The results indicated that the ζ potentials measured by streaming potential method were significantly correlated with the ζ potentials of soil colloids determined by electrophoresis (r (2) = 0.960**). Therefore, the streaming potential method can be used to study the ζ potentials of bulk clay soils. The absolute values of the ζ potentials of four soils followed the order: Ultisol from Jiangxi > Ultisol from Anhui > Oxisol from Guangdong > Oxisol from Hainan, and this was consistent with the cation exchange capacities of these soils. The type and concentration of electrolytes affected soil ζ potentials. The ζ potential became less negative with increased electrolyte concentration. The ζ potentials were more negative in monovalent than in divalent cationic electrolyte solutions because more divalent cations were distributed in the shear plane of the diffuse layer as counter-cations on the soil surfaces than monovalent cations at the same electrolyte concentration.

  7. What is baseflow? Integrating hydrometric and hydrochemical methods to assess dynamic groundwater contributions to montane streams under low flows

    Blumstock, Maria; Tetzlaff, Doerthe; Nuetzmann, Gunnar; Malcolm, Iain; Soulsby, Chris


    We monitored changing groundwater-surface water interactions through an unusual prolonged dry spell in the Scottish Highlands in summer 2013. The period between May and September saw a 20 year return period drought, these changing hydrometric conditions were monitored in an intensively instrumented 3.2km2 catchment. This montane catchment is underlain by granite and metasediments and has extensive cover of diverse drift deposits. The drought saw slight declines in soil moisture and groundwater levels in valley bottom wetlands but major, rapid declines on steeper upland slopes. This coincided with gradual declines in discharge, however the chemical composition of reducing stream flows showed marked temporal variation which differed spatially. Synoptic hydrogeochemical surveys were carried out on four occasions as flows declined. Each survey repeated sampling of 30 sites on the 3km long stream network as the catchment transitioned from wet to dry conditions. Samples were analysed for major anions, cations and water isotopes. Initial surveys just after the last winter rain showed relatively homogenous stream chemistry, dominated by drainage from acidic peat soils in valley bottom areas. Stream chemistry became increasingly enriched with weathering-derived solutes (e.g. alkalinity, Ca, Mg etc.) as flows declined and groundwater contributions to flow increases. Repeat surveys showed an evolving chemistry of groundwater contributions as discharge from smaller shallower stores sequentially depleted. However, these changes showed marked spatial variability reflecting geochemical differences in the bedrock geology and the distribution of drift deposits. Importantly, much more dynamism was observed than previously thought with diverse montane groundwater bodies contributing to flows differentially during the recession. In addition, strong topographic shading in this montane catchment results in spatially variable radiation inputs and evapotranspiration. This is reflected in

  8. A biological tool to assess flow connectivity in reference temporary streams from the Mediterranean Basin

    Cid, N., E-mail: [Grup de Recerca “Freshwater Ecology and Management (FEM)”, Departament d' Ecologia, Universitat de Barcelona, Catalonia (Spain); Verkaik, I. [Grup de Recerca “Freshwater Ecology and Management (FEM)”, Departament d' Ecologia, Universitat de Barcelona, Catalonia (Spain); García-Roger, E.M. [Grup de Recerca “Freshwater Ecology and Management (FEM)”, Departament d' Ecologia, Universitat de Barcelona, Catalonia (Spain); Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València (Spain); Rieradevall, M.; Bonada, N. [Grup de Recerca “Freshwater Ecology and Management (FEM)”, Departament d' Ecologia, Universitat de Barcelona, Catalonia (Spain); Sánchez-Montoya, M.M. [Department of Ecology and Hydrology, Regional Campus of International Excellence “Campus Mare Nostrum”—University of Murcia (Spain); Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin (Germany); Gómez, R.; Suárez, M.L.; Vidal-Abarca, M.R. [Department of Ecology and Hydrology, Regional Campus of International Excellence “Campus Mare Nostrum”—University of Murcia (Spain); Demartini, D.; Buffagni, A.; Erba, S. [Instituto di Ricerca Sulle Acque (CNR-IRSA) (Italy); Karaouzas, I.; Skoulikidis, N. [Hellenic Center for Marine Research (HCMR) (Greece); Prat, N. [Grup de Recerca “Freshwater Ecology and Management (FEM)”, Departament d' Ecologia, Universitat de Barcelona, Catalonia (Spain)


    Many streams in the Mediterranean Basin have temporary flow regimes. While timing for seasonal drought is predictable, they undergo strong inter-annual variability in flow intensity. This high hydrological variability and associated ecological responses challenge the ecological status assessment of temporary streams, particularly when setting reference conditions. This study examined the effects of flow connectivity in aquatic macroinvertebrates from seven reference temporary streams across the Mediterranean Basin where hydrological variability and flow conditions are well studied. We tested for the effect of flow cessation on two streamflow indices and on community composition, and, by performing random forest and classification tree analyses we identified important biological predictors for classifying the aquatic state either as flowing or disconnected pools. Flow cessation was critical for one of the streamflow indices studied and for community composition. Macroinvertebrate families found to be important for classifying the aquatic state were Hydrophilidae, Simuliidae, Hydropsychidae, Planorbiidae, Heptageniidae and Gerridae. For biological traits, trait categories associated to feeding habits, food, locomotion and substrate relation were the most important and provided more accurate predictions compared to taxonomy. A combination of selected metrics and associated thresholds based on the most important biological predictors (i.e. Bio-AS Tool) were proposed in order to assess the aquatic state in reference temporary streams, especially in the absence of hydrological data. Although further development is needed, the tool can be of particular interest for monitoring, restoration, and conservation purposes, representing an important step towards an adequate management of temporary rivers not only in the Mediterranean Basin but also in other regions vulnerable to the effects of climate change. - Highlights: • The effect of flow connectivity on macroinvertebrate

  9. Experimental studies of the streaming flow due to the adsorption of particles at a liquid surface

    Singh, Pushpendra; Musunuri, Naga; Fischer, Ian


    The particle image velocimetry (PIV) technique is used to study the streaming flow that is induced when particles are adsorbed at a liquid surface. The flow develops within a fraction of second after the adsorption of the particle and persists for several seconds. The fluid directly below the particle rises upward, and near the surface, it moves away from the particle. The flow causes powders sprinkled on a liquid surface to disperse on the surface. The flow strength, and the volume over which it extends, decreases with decreasing particle size. The streaming flow induced by the adsorption of two or more particles is a combination of the flows which they induce individually. The work was supported by National Science Foundation.

  10. Users Manual for the Geospatial Stream Flow Model (GeoSFM)

    Artan, Guleid A.; Asante, Kwabena; Smith, Jodie; Pervez, Md Shahriar; Entenmann, Debbie; Verdin, James P.; Rowland, James


    The monitoring of wide-area hydrologic events requires the manipulation of large amounts of geospatial and time series data into concise information products that characterize the location and magnitude of the event. To perform these manipulations, scientists at the U.S. Geological Survey Center for Earth Resources Observation and Science (EROS), with the cooperation of the U.S. Agency for International Development, Office of Foreign Disaster Assistance (USAID/OFDA), have implemented a hydrologic modeling system. The system includes a data assimilation component to generate data for a Geospatial Stream Flow Model (GeoSFM) that can be run operationally to identify and map wide-area streamflow anomalies. GeoSFM integrates a geographical information system (GIS) for geospatial preprocessing and postprocessing tasks and hydrologic modeling routines implemented as dynamically linked libraries (DLLs) for time series manipulations. Model results include maps that depicting the status of streamflow and soil water conditions. This Users Manual provides step-by-step instructions for running the model and for downloading and processing the input data required for initial model parameterization and daily operation.

  11. Tuning hydrological models for ecological modeling - improving simulations of low flows critical to stream ecology

    Olsen, Martin; Troldborg, Lars; Boegh, Eva


    The consequences of using simulated discharge from a conventional hydrological model as input in stream physical habitat modelling was investigated using output from the Danish national hydrological model and a physical habitat model of three small streams. It was found that low flow simulation...... errors could have large impact on simulation of physical habitat conditions. If these two models are to be used to assess groundwater abstraction impact on physical habitat conditions the hydrological model should be tuned to the purpose...

  12. Tuning hydrological models for ecological modeling - improving simulations of low flows critical to stream ecology

    Olsen, Martin; Troldborg, Lars; Boegh, Eva;


    The consequences of using simulated discharge from a conventional hydrological model as input in stream physical habitat modelling was investigated using output from the Danish national hydrological model and a physical habitat model of three small streams. It was found that low flow simulation...... errors could have large impact on simulation of physical habitat conditions. If these two models are to be used to assess groundwater abstraction impact on physical habitat conditions the hydrological model should be tuned to the purpose...

  13. Estimates of Median Flows for Streams on the 1999 Kansas Surface Water Register

    Perry, Charles A.; Wolock, David M.; Artman, Joshua C.


    The Kansas State Legislature, by enacting Kansas Statute KSA 82a?2001 et. seq., mandated the criteria for determining which Kansas stream segments would be subject to classification by the State. One criterion for the selection as a classified stream segment is based on the statistic of median flow being equal to or greater than 1 cubic foot per second. As specified by KSA 82a?2001 et. seq., median flows were determined from U.S. Geological Survey streamflow-gaging-station data by using the most-recent 10 years of gaged data (KSA) for each streamflow-gaging station. Median flows also were determined by using gaged data from the entire period of record (all-available hydrology, AAH). Least-squares multiple regression techniques were used, along with Tobit analyses, to develop equations for estimating median flows for uncontrolled stream segments. The drainage area of the gaging stations on uncontrolled stream segments used in the regression analyses ranged from 2.06 to 12,004 square miles. A logarithmic transformation of the data was needed to develop the best linear relation for computing median flows. In the regression analyses, the significant climatic and basin characteristics, in order of importance, were drainage area, mean annual precipitation, mean basin permeability, and mean basin slope. Tobit analyses of KSA data yielded a model standard error of prediction of 0.285 logarithmic units, and the best equations using Tobit analyses of AAH data had a model standard error of prediction of 0.250 logarithmic units. These regression equations and an interpolation procedure were used to compute median flows for the uncontrolled stream segments on the 1999 Kansas Surface Water Register. Measured median flows from gaging stations were incorporated into the regression-estimated median flows along the stream segments where available. The segments that were uncontrolled were interpolated using gaged data weighted according to the drainage area and the bias between the

  14. Evidence of climate change impact on stream low flow from the tropical mountain rainforest watershed in Hainan Island, China

    Z. Zhou; Y. Ouyang; Z. Qiu; G. Zhou; M. Lin; Y. Li


    Stream low flow estimates are central to assessing climate change impact, water resource management, and ecosystem restoration. This study investigated the impacts of climate change upon stream low flows from a rainforest watershed in Jianfengling (JFL) Mountain, Hainan Island, China, using the low flow selection method as well as the frequency and probability analysis...

  15. A framework for estimating the occurrence frequency and dominant controls of preferential flow across diverse soil-landscapes

    Lin, H.; Guo, L.


    Preferential flow can occur in practically all soils and landscapes and has significant impacts on water quantity and quality, stream discharge, groundwater recharge, contaminant transport, biogeochemical dynamics, and many other environmental and ecological processes. However, due to limited methods available to quantify and monitor preferential flow in the field, the frequency and controls of preferential flow occurrence remain poorly understood. This study examines various methods for identifying and quantifying preferential flow occurrence across space and time and its dominant controls under various field conditions. Based on data collected from a forest catchment and a farm land, we discuss soil moisture sensor networks that provide new opportunities to characterize preferential flow occurrence in real time. We summarize spatial factors that influence preferential flow occurrence, including landscape features (such as landform, hillslope type/shape, slope, and underlying bedrock), soil properties (such as soil type, texture, layering, and structure), and land use/land cover (such as vegetation type and management practices). Temporal factors influencing preferential flow occurrence include precipitation characteristics (such as amount, intensity, duration, and timing), initial soil moisture condition (such as dry, moist, and wet), and vegetation dynamics (such as canopy cover and root growth). We organize these six key categories of factors into an overarching framework for estimating the occurrence frequency and dominant controls of preferential flow across diverse soil-landscapes. Finally, we address optimal experimental design for preferential flow investigation in the field and provide a future outlook on new research opportunities.

  16. Improving AVSWAT Stream Flow Simulation by Incorporating Groundwater Recharge Prediction in the Upstream Lesti Watershed, East Java, Indonesia

    Christina Rahayuningtyas


    Full Text Available The upstream Lesti watershed is one of the major watersheds of East Java in Indonesia, covering about 38093 hectares. Although there are enough water resources to meet current demands in the basin, many challenges including high spatial and temporal variability in precipitation from year to year exist. It is essential to understand how the climatic condition affects Lesti River stream flow in each sub basin. This study investigated the applicability of using the Soil and Water Assessment Tool (SWAT with the incorporation of groundwater recharge prediction in stream flow simulation in the upstream Lesti watershed. Four observation wells in the upstream Lesti watershed were used to evaluate the seasonal and annual variations in the water level and estimate the groundwater recharge in the deep aquifer. The results show that annual water level rise was within the 2800 - 5700 mm range in 2007, 3900 - 4700 mm in 2008, 3200 - 5100 mm in 2009, and 2800 - 4600 mm in 2010. Based on the specific yield and the measured water level rise, the area-weighted groundwater predictions at the watershed outlet are 736, 820.9, 786.7, 306.4 mm in 2007, 2008, 2009, and 2010, respectively. The consistency test reveals that the R-square statistical value is greater than 0.7, and the DV (% ranged from 32 - 55.3% in 2007 - 2010. Overall, the SWAT model performs better in the wet season flow simulation than the dry season. It is suggested that the SWAT model needs to be improved for stream flow simulation in tropical regions.

  17. Estimating selected low-flow frequency statistics and harmonic-mean flows for ungaged, unregulated streams in Indiana

    Martin, Gary R.; Fowler, Kathleen K.; Arihood, Leslie D.


    Information on low-flow characteristics of streams is essential for the management of water resources. This report provides equations for estimating the 1-, 7-, and 30-day mean low flows for a recurrence interval of 10 years and the harmonic-mean flow at ungaged, unregulated stream sites in Indiana. These equations were developed using the low-flow statistics and basin characteristics for 108 continuous-record streamgages in Indiana with at least 10 years of daily mean streamflow data through the 2011 climate year (April 1 through March 31). The equations were developed in cooperation with the Indiana Department of Environmental Management.Regression techniques were used to develop the equations for estimating low-flow frequency statistics and the harmonic-mean flows on the basis of drainage-basin characteristics. A geographic information system was used to measure basin characteristics for selected streamgages. A final set of 25 basin characteristics measured at all the streamgages were evaluated to choose the best predictors of the low-flow statistics.Logistic-regression equations applicable statewide are presented for estimating the probability that selected low-flow frequency statistics equal zero. These equations use the explanatory variables total drainage area, average transmissivity of the full thickness of the unconsolidated deposits within 1,000 feet of the stream network, and latitude of the basin outlet. The percentage of the streamgage low-flow statistics correctly classified as zero or nonzero using the logistic-regression equations ranged from 86.1 to 88.9 percent.Generalized-least-squares regression equations applicable statewide for estimating nonzero low-flow frequency statistics use total drainage area, the average hydraulic conductivity of the top 70 feet of unconsolidated deposits, the slope of the basin, and the index of permeability and thickness of the Quaternary surficial sediments as explanatory variables. The average standard error of

  18. Streaming driven by sessile microbubbles: Explaining flow patterns and frequency response

    Rallabandi, Bhargav; Wang, Cheng; Guo, Lin; Hilgenfeldt, Sascha


    Ultrasound excitation of bubbles drives powerful steady streaming flows which have found widespread applications in microfluidics, where bubbles are typically of semicircular cross section and attached to walls of the device (sessile). While bubble-driven streaming in bulk fluid is well understood, this practically relevant case presents additional complexity introduced by the wall and contact lines. We develop an asymptotic theory that takes into account the presence of the wall as well as the oscillation dynamics of the bubble, providing a complete description of the streaming flow as a function only of the driving frequency, the bubble size, and the physical properties of the fluid. We show that the coupling between different bubble oscillation modes sustains the experimentally observed streaming flow vortex pattern over a broad range of frequencies, greatly exceeding the widths of individual mode resonances. Above a threshold frequency, we predict, and observe in experiment, reversal of the flow direction. Our analytical theory can be used to guide the design of microfluidic devices, both in situations where robust flow patterns insensitive to parameter changes are desired (e.g. lab-on-a-chip sorters), and in cases where intentional modulation of the flow field appearance is key (e.g. efficient mixers). Current address: Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology.

  19. IOD and ENSO impacts on the extreme stream-flows of Citarum river in Indonesia

    Sahu, Netrananda; Behera, Swadhin K.; Yamashiki, Yosuke; Takara, Kaoru; Yamagata, Toshio


    Extreme stream-flow events of Citarum River are derived from the daily stream-flows at the Nanjung gauge station. Those events are identified based on their persistently extreme flows for 6 or more days during boreal fall when the seasonal mean stream-flow starts peaking-up from the lowest seasonal flows of June-August. Most of the extreme events of high-streamflows were related to La Niña conditions of tropical Pacific. A few of them were also associated with the negative phases of IOD and the newly identified El Niño Modoki. Unlike the cases of extreme high streamflows, extreme low streamflow events are seen to be associated with the positive IODs. Nevertheless, it was also found that the low-stream-flow events related to positive IOD events were also associated with El Niño events except for one independent event of 1977. Because the occurrence season coincides the peak season of IOD, not only the picked extreme events are seen to fall under the IOD seasons but also there exists a statistically significant correlation of 0.51 between the seasonal IOD index and the seasonal streamflows. There also exists a significant lag correlation when IOD of June-August season leads the streamflows of September-November. A significant but lower correlation coefficient (0.39) is also found between the seasonal streamflow and El Niño for September-November season only.

  20. Development and Application of Flow Duration Curves for Stream Restoration


    They have traditionally been used for a variety of purposes from hydropower engineering to instream flow quantification. This paper serves to ( disproportionately large roles in shaping ERDC TN-EMRRP-SR-49 February 2016 8 channel morphology by doing the most “geomorphic work ” over...Discharge Probability Sediment Rating (ton/da) Geomorphic Work Figure 6. Effective discharge application of flow duration curves for the Etowah River at

  1. Solar forcing of the stream flow of a continental scale South American river.

    Mauas, Pablo J D; Flamenco, Eduardo; Buccino, Andrea P


    Solar forcing on climate has been reported in several studies although the evidence so far remains inconclusive. Here, we analyze the stream flow of one of the largest rivers in the world, the Paraná in southeastern South America. For the last century, we find a strong correlation with the sunspot number, in multidecadal time scales, and with larger solar activity corresponding to larger stream flow. The correlation coefficient is r=0.78, significant to a 99% level. In shorter time scales we find a strong correlation with El Niño. These results are a step toward flood prediction, which might have great social and economic impacts.


    Godsk, Mikkel

    This paper presents a flexible model, ‘STREAM’, for transforming higher science education into blended and online learning. The model is inspired by ideas of active and collaborative learning and builds on feedback strategies well-known from Just-in-Time Teaching, Flipped Classroom, and Peer...... Instruction. The aim of the model is to provide both a concrete and comprehensible design toolkit for adopting and implementing educational technologies in higher science teaching practice and at the same time comply with diverse ambitions. As opposed to the above-mentioned feedback strategies, the STREAM...

  3. Streaming flow from ultrasound contrast agents by acoustic waves in a blood vessel model.

    Cho, Eunjin; Chung, Sang Kug; Rhee, Kyehan


    To elucidate the effects of streaming flow on ultrasound contrast agent (UCA)-assisted drug delivery, streaming velocity fields from sonicated UCA microbubbles were measured using particle image velocimetry (PIV) in a blood vessel model. At the beginning of ultrasound sonication, the UCA bubbles formed clusters and translated in the direction of the ultrasound field. Bubble cluster formation and translation were faster with 2.25MHz sonication, a frequency close to the resonance frequency of the UCA. Translation of bubble clusters induced streaming jet flow that impinged on the vessel wall, forming symmetric vortices. The maximum streaming velocity was about 60mm/s at 2.25MHz and decreased to 15mm/s at 1.0MHz for the same acoustic pressure amplitude. The effect of the ultrasound frequency on wall shear stress was more noticeable. Maximum wall shear stress decreased from 0.84 to 0.1Pa as the ultrasound frequency decreased from 2.25 to 1.0MHz. The maximum spatial gradient of the wall shear stress also decreased from 1.0 to 0.1Pa/mm. This study showed that streaming flow was induced by bubble cluster formation and translation and was stronger upon sonication by an acoustic wave with a frequency near the UCA resonance frequency. Therefore, the secondary radiant force, which is much stronger at the resonance frequency, should play an important role in UCA-assisted drug delivery.

  4. Review of samples of tailings, soils and stream sediment adjacent to and downstream from the Ruth Mine, Inyo County, California

    Rytuba, James J.; Kim, Christopher S.; Goldstein, Daniel N.


    The Ruth Mine and mill are located in the western Mojave Desert in Inyo County, California (fig. 1). The mill processed gold-silver (Au-Ag) ores mined from the Ruth Au-Ag deposit, which is adjacent to the mill site. The Ruth Au-Ag deposit is hosted in Mesozoic intrusive rocks and is similar to other Au-Ag deposits in the western Mojave Desert that are associated with Miocene volcanic centers that formed on a basement of Mesozoic granitic rocks (Bateman, 1907; Gardner, 1954; Rytuba, 1996). The volcanic rocks consist of silicic domes and associated flows, pyroclastic rocks, and subvolcanic intrusions (fig. 2) that were emplaced into Mesozoic silicic intrusive rocks (Troxel and Morton, 1962). The Ruth Mine is on Federal land managed by the U.S. Bureau of Land Management (BLM). Tailings from the mine have been eroded and transported downstream into Homewood Canyon and then into Searles Valley (figs. 3, 4, 5, and 6). The BLM provided recreational facilities at the mine site for day-use hikers and restored and maintained the original mine buildings in collaboration with local citizen groups for use by visitors (fig. 7). The BLM requested that the U.S. Geological Survey (USGS), in collaboration with Chapman University, measure arsenic (As) and other geochemical constituents in soils and tailings at the mine site and in stream sediments downstream from the mine in Homewood Canyon and in Searles Valley (fig. 3). The request was made because initial sampling of the site by BLM staff indicated high concentrations of As in tailings and soils adjacent to the Ruth Mine. This report summarizes data obtained from field sampling of mine tailings and soils adjacent to the Ruth Mine and stream sediments downstream from the mine on June 7, 2009. Our results permit a preliminary assessment of the sources of As and associated chemical constituents that could potentially impact humans and biota.

  5. Soil Erosion from Agriculture and Mining: A Threat to Tropical Stream Ecosystems

    Jan H. Mol


    Full Text Available In tropical countries soil erosion is often increased due to high erodibility of geologically old and weathered soils; intensive rainfall; inappropriate soil management; removal of forest vegetation cover; and mining activities. Stream ecosystems draining agricultural or mining areas are often severely impacted by the high loads of eroded material entering the stream channel; increasing turbidity; covering instream habitat and affecting the riparian zone; and thereby modifying habitat and food web structures. The biodiversity is severely threatened by these negative effects as the aquatic and riparian fauna and flora are not adapted to cope with excessive rates of erosion and sedimentation. Eroded material may also be polluted by pesticides or heavy metals that have an aggravating effect on functions and ecosystem services. Loss of superficial material and deepening of erosion gullies impoverish the nutrient and carbon contents of the soils; and lower the water tables; causing a “lose-lose” situation for agricultural productivity and environmental integrity. Several examples show how to interrupt this vicious cycle by integrated catchment management and by combining “green” and “hard” engineering for habitat restoration. In this review; we summarize current findings on this issue from tropical countries with a focus on case studies from Suriname and Brazil.

  6. Integration of manual channel initiation and flow path tracing in extracting stream features from lidar-derived DTM

    Gaspa, M. C.; De La Cruz, R. M.; Olfindo, N. T.; Borlongan, N. J. B.; Perez, A. M. C.


    Stream network delineation based on LiDAR-derived digital terrain model (DTM) may produce stream segments that are inexistent or incomplete because of limitations imposed by extraction procedure, terrain and data. The applicability of a common threshold value in defining streams such as those implemented through the D8 algorithm also remains in question because the threshold varies depending on the geomorphology of the area. Flat areas and improper hydrologic conditioning produce erratic stream network. To counteract these limitations, this study proposes a workflow that improves the stream network produced by the D8 algorithm. It incorporates user-defined channel initiation points as inputs to a tool developed to automatically trace the flow of water into the next actual stream segment. Spurious streams along digital dams and flat areas are also manually reshaped. The proposed workflow is implemented in Iligan River Basin, Philippines using LiDARderived DTM of 1-meter resolution. The Flow Path Tracing (FPT) method counteracts the limits imposed by extraction procedure, terrain and data. It is applicable to different typologies of watersheds by eliminating the need to use site-specific threshold in determining streams. FPT is implemented as a Phyton script to automate the tracing of the streams using the flow direction raster. The FPT method is compared to the blue line digitization and the D8 method using morphometric parameters, such as stream number, stream order and stream length, to assess its performance. Results show that streams derived from the FPT method has higher stream order, number and length. An accuracy of 93.5% produced from field validation of the FPT method's streams strengthens the findings that integrating manual channel head initiation and flow path tracing can be used for nationwide extraction of streams using LiDAR-derived-DTM in the Philippines.

  7. Validating alternative methodologies to estimate the hydrological regime of temporary streams when flow data are unavailable

    Llorens, Pilar; Gallart, Francesc; Latron, Jérôme; Cid, Núria; Rieradevall, Maria; Prat, Narcís


    Aquatic life in temporary streams is strongly conditioned by the temporal variability of the hydrological conditions that control the occurrence and connectivity of diverse mesohabitats. In this context, the software TREHS (Temporary Rivers' Ecological and Hydrological Status) has been developed, in the framework of the LIFE Trivers project, to help managers for adequately implement the Water Framework Directive in this type of water bodies. TREHS, using the methodology described in Gallart et al (2012), defines six temporal 'aquatic states', based on the hydrological conditions representing different mesohabitats, for a given reach at a particular moment. Nevertheless, hydrological data for assessing the regime of temporary streams are often non-existent or scarce. The scarcity of flow data makes frequently impossible the characterization of temporary streams hydrological regimes and, as a consequence, the selection of the correct periods and methods to determine their ecological status. Because of its qualitative nature, the TREHS approach allows the use of alternative methodologies to assess the regime of temporary streams in the lack of observed flow data. However, to adapt the TREHS to this qualitative data both the temporal scheme (from monthly to seasonal) as well as the number of aquatic states (from 6 to 3) have been modified. Two alternatives complementary methodologies were tested within the TREHS framework to assess the regime of temporary streams: interviews and aerial photographs. All the gauging stations (13) belonging to the Catalan Internal Catchments (NE, Spain) with recurrent zero flows periods were selected to validate both methodologies. On one hand, non-structured interviews were carried out to inhabitants of villages and small towns near the gauging stations. Flow permanence metrics for input into TREHS were drawn from the notes taken during the interviews. On the other hand, the historical series of available aerial photographs (typically 10

  8. Flume Experiment on Stream Blockage by the Debris Flow From Tributary


    Stream blockage by the debris flow from tributary valleys is a common phenomenon in mountainous area,which takes place when large quantities of sediment transported by debris flow reaches a river channel causing its complete or partial blockage.The dam formed by debris flow may causes upstream and downstream flooding,and presents great threat to people and property.Because of the catastrophic influence on people and property,debris-flow dam has attracted many attentions from the researchers and local adm...

  9. Effects of in-stream structures and channel flow rate variation on transient storage

    Rana, S. M. Masud; Scott, Durelle T.; Hester, Erich T.


    In-stream structures can potentially enhance surface and subsurface solute retention. They form naturally in small streams and their installation has gained popularity in stream restoration for multiple purposes, including improved water quality. Yet few studies have quantified the cumulative effect of multiple structures on solute transport at the reach scale, nor how this varies with changing stream flow. We built a series of weirs in a small stream to simulate channel spanning structures such as natural debris dams and stream restoration log dams and boulder weirs. We conducted constant rate conservative (NaCl) tracer injections to quantify the effect of the weirs on solute transport at the reach scale. We used a one dimensional solute transport model with transient storage to quantify the change of solute transport parameters with increasing number of weirs. Results indicate that adding weirs significantly increased the cross-sectional area of the surface stream (A) and transient storage zones (As) while exchange with transient storage (α) decreased. The increase in A and As is due to backwater behind weirs and increased hydrostatically driven hyporheic exchange induced by the weirs, while we surmise that the reduction in α is due at least in part to reduced hydrodynamically driven hyporheic exchange in bed ripples drowned by the weir backwater. In order for weir installation to achieve net improvement in solute retention and thus water quality, cumulative reactions in weir backwater and enhanced hydrostatically driven hyporheic exchange would have to overcome the reduced hydrodynamically driven exchange. Analysis of channel flow variation over the course of the experiments indicated that weirs change the relationship between transient storage parameters and flow, for example the trend of increasing α with flow without weirs was reversed in the presence of weirs. Effects of flow variation were substantial, indicating that transient storage measurements at a

  10. Hydrologic connectivity to streams increases nitrogen and phosphorus inputs and cycling in soils of created and natural floodplain wetlands.

    Wolf, Kristin L; Noe, Gregory B; Ahn, Changwoo


    Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots ( = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed.

  11. Hydrochemical heterogeneity in an upland catchment: further characterisation of the spatial, temporal and depth variations in soils, streams and groundwaters of the Plynlimon forested catchment, Wales

    P. Shand


    Full Text Available The heterogeneous nature of upland hard-rock catchments in terms of geology, geomorphology, superficial deposits, soil type and land use gives rise to a range of hydrochemical characteristics in stream waters. This is further complicated by the large and often rapid changes in stream flow typical of storm events. The sources of solutes and flow pathways in hard-rock catchments are still poorly understood, in particular the role of bedrock groundwater. Spatial variations in water chemistry are presented for stream waters, soils and groundwaters in the forested Plynlimon catchment of Wales, UK. The results highlight a large degree of spatial heterogeneity in each of these systems. This has major implications for the application of end-member mixing analysis and presents serious problems for modelling in scaling up from study sites to catchment scale. However, such data provide important constraints on sources, flow pathways and residence times within individual catchment compartments, knowledge of which is essential for understanding how such catchments function. The characterisation of sub-surface waters in upland catchments requires a great deal of care during sampling as well as high spatial and temporal resolution of sampling, and further work is required to characterise the Plynlimon catchments fully. Nevertheless, the presence of an active and highly stratified groundwater system is considered important as a source of solutes and water to streams. It also provides a storage medium that is likely to make a major contribution to explaining the strongly damped rainfall Cl and d2H signals measured in the streams.

  12. Unsteady Boundary-Layer Flow over Jerked Plate Moving in a Free Stream of Viscoelastic Fluid

    Sufian Munawar


    Full Text Available This study aims to investigate the unsteady boundary-layer flow of a viscoelastic non-Newtonian fluid over a flat surface. The plate is suddenly jerked to move with uniform velocity in a uniform stream of non-Newtonian fluid. Purely analytic solution to governing nonlinear equation is obtained. The solution is highly accurate and valid for all values of the dimensionless time 0≤τ<∞. Flow properties of the viscoelastic fluid are discussed through graphs.

  13. Classification of the Group Invariant Solutions for Contaminant Transport in Saturated Soils under Radial Uniform Water Flows

    M. M. Potsane


    Full Text Available The transport of chemicals through soils to the groundwater or precipitation at the soils surfaces leads to degradation of these resources. Serious consequences may be suffered in the long run. In this paper, we consider macroscopic deterministic models describing contaminant transport in saturated soils under uniform radial water flow backgrounds. The arising convection-dispersion equation given in terms of the stream functions is analyzed using classical Lie point symmetries. A number of exotic Lie point symmetries are admitted. Group invariant solutions are classified according to the elements of the one-dimensional optimal systems. We analyzed the group invariant solutions which satisfy the physical boundary conditions.

  14. Theoretical aspects of electrical power generation from two-phase flow streaming potentials

    Sherwood, J.D.; Xie, Yanbo; van den Berg, Albert; Eijkel, Jan C.T.

    A theoretical analysis of the generation of electrical streaming currents and electrical power by two-phase flow in a rectangular capillary is presented. The injection of a second, non-conducting fluid phase tends to increase the internal electrical resistance of the electrical generator, thereby

  15. Assessment of Short Term Rainfall and Stream Flows in South Australia

    Mohammad Kamruzzaman


    Full Text Available The aim of this study is to assess the relationship between rainfall and stream flow at Broughton River in Mooroola, Torrance River in Mount Pleasant, and Wakefield River near Rhyine, in South Australia, from 1990 to 2010. Initially, we present a short term relationship between rainfall and stream flow, in terms of correlations, lagged correlations, and estimated variability between wavelet coefficients at each level. A deterministic regression based response model is used to detect linear, quadratic and polynomial trends, while allowing for seasonality effects. Antecedent rainfall data were considered to predict stream flow. The best fitting model was selected based on maximum adjusted R2 values (R2adj , minimum sigma square (σ2, and a minimum Akaike Information Criterion (AIC. The best performance in the response model is lag rainfall, which indicates at least one day and up to 7 days (past difference in rainfall, including offset cross products of lag rainfall. With the inclusion of antecedent stream flow as an input with one day time lag, the result shows a significant improvement of the R2adj values from 0.18, 0.26 and 0.14 to 0.35, 0.42 and 0.21 at Broughton River, Torrance River and Wakefield River, respectively. A benchmark comparison was made with an Artificial Neural Network analysis. The optimization strategy involved adopting a minimum mean absolute error (MAE.

  16. Constraints upon the response of fish and crayfish to environmental flow releases in a regulated headwater stream network.

    Chester, Edwin T; Matthews, Ty G; Howson, Travis J; Johnston, Kerrylyn; Mackie, Jonathon K; Strachan, Scott R; Robson, Belinda J


    In dry climate zones, headwater streams are often regulated for water extraction causing intermittency in perennial streams and prolonged drying in intermittent streams. Regulation thereby reduces aquatic habitat downstream of weirs that also form barriers to migration by stream fauna. Environmental flow releases may restore streamflow in rivers, but are rarely applied to headwaters. We sampled fish and crayfish in four regulated headwater streams before and after the release of summer-autumn environmental flows, and in four nearby unregulated streams, to determine whether their abundances increased in response to flow releases. Historical data of fish and crayfish occurrence spanning a 30 year period was compared with contemporary data (electrofishing surveys, Victoria Range, Australia; summer 2008 to summer 2010) to assess the longer-term effects of regulation and drought. Although fish were recorded in regulated streams before 1996, they were not recorded in the present study upstream or downstream of weirs despite recent flow releases. Crayfish (Geocharax sp. nov. 1) remained in the regulated streams throughout the study, but did not become more abundant in response to flow releases. In contrast, native fish (Gadopsis marmoratus, Galaxias oliros, Galaxias maculatus) and crayfish remained present in unregulated streams, despite prolonged drought conditions during 2006-2010, and the assemblages of each of these streams remained essentially unchanged over the 30 year period. Flow release volumes may have been too small or have operated for an insufficient time to allow fish to recolonise regulated streams. Barriers to dispersal may also be preventing recolonisation. Indefinite continuation of annual flow releases, that prevent the unnatural cessation of flow caused by weirs, may eventually facilitate upstream movement of fish and crayfish in regulated channels; but other human-made dispersal barriers downstream need to be identified and ameliorated, to allow

  17. Constraints upon the response of fish and crayfish to environmental flow releases in a regulated headwater stream network.

    Edwin T Chester

    Full Text Available In dry climate zones, headwater streams are often regulated for water extraction causing intermittency in perennial streams and prolonged drying in intermittent streams. Regulation thereby reduces aquatic habitat downstream of weirs that also form barriers to migration by stream fauna. Environmental flow releases may restore streamflow in rivers, but are rarely applied to headwaters. We sampled fish and crayfish in four regulated headwater streams before and after the release of summer-autumn environmental flows, and in four nearby unregulated streams, to determine whether their abundances increased in response to flow releases. Historical data of fish and crayfish occurrence spanning a 30 year period was compared with contemporary data (electrofishing surveys, Victoria Range, Australia; summer 2008 to summer 2010 to assess the longer-term effects of regulation and drought. Although fish were recorded in regulated streams before 1996, they were not recorded in the present study upstream or downstream of weirs despite recent flow releases. Crayfish (Geocharax sp. nov. 1 remained in the regulated streams throughout the study, but did not become more abundant in response to flow releases. In contrast, native fish (Gadopsis marmoratus, Galaxias oliros, Galaxias maculatus and crayfish remained present in unregulated streams, despite prolonged drought conditions during 2006-2010, and the assemblages of each of these streams remained essentially unchanged over the 30 year period. Flow release volumes may have been too small or have operated for an insufficient time to allow fish to recolonise regulated streams. Barriers to dispersal may also be preventing recolonisation. Indefinite continuation of annual flow releases, that prevent the unnatural cessation of flow caused by weirs, may eventually facilitate upstream movement of fish and crayfish in regulated channels; but other human-made dispersal barriers downstream need to be identified and

  18. Distribution of Amphipods (Gammarus nipponensis Ueno) Among Mountain Headwater Streams with Different Legacies of Debris Flow Occurrence

    To understand the impacts of debris flows on the distribution of an amphipod with limited dispersal ability in the context of stream networks, we surveyed the presence of Gammarus nipponensis in 87 headwater streams with different legacies of debris flow occurrence within an 8.5-...

  19. Stream Water and Soil Water Chemistry Following the Table Mountain Wildfire, Washington

    Roccanova, V. J.; Gazis, C. A.


    Severe wildfire occurrence in the Western United States increased throughout the 20th century and has continued to increase into the 21st century. Global climate change resulting from natural and anthropogenic sources is considered a contributor to this increase in wildfire severity. Fire suppression techniques developed in the early 20th century are also a factor in increased severe wildfire occurrence as they augment available fuel loads. Biomass burning releases nutrients that are held within trees and plants. Nitrogen, phosphorous, and calcium levels have been documented as increasing in stream waters as a result of wildfire. As severe wildfire occurrence increases, so does the likelihood that stream, and to a lesser extent groundwater, will be loaded with nutrients and sediments as a result of wildfire activity. Increased nutrient loads can cause algal blooms that deplete streams of oxygen, important to aquatic plants and animals that reside in these streams. These changes in water quality can also affect humans who depend on these streams for irrigation and drinking water purposes. The Table Mountain wildfire in Washington State was started by a lightning strike that occurred at approximately 8:00 PM on Saturday September 8th, 2012. The fire burned for approximately one month and was declared to be 100% contained on Friday October 5th, 2012. Over this period the fire burned a total of 171 square kilometers of forest. In this study multiple stream and soil water samples were collected from three types of area in the winter through summer following the fire: severely burned, moderately burned, and unburned. All areas sampled have similar bedrock and vegetation cover. These samples were analyzed for major ions and trace element concentrations. Select samples will also be analyzed for strontium isotope ratios. The results of these geochemical analyses will be presented. Because calcium and strontium have similar properties, their concentrations can be combined

  20. Morphodynamic Response of Laboratory Stream Beds to Unsteady Flow Events of Varying Magnitude and Duration

    Binns, A. D.; Gunsolus, E. H.


    Natural processes and anthropogenic activities can cause short-term flow increases in rivers. These changes in flow, such as those caused by extreme rainfall events or seasonal variation in precipitation patterns, can result in substantial, and sometimes quite rapid, adjustments in sediment regime and alluvial stream morphology. Such morphological adjustments can pose short-term erosion hazards, increased risk of flooding, degradation to aquatic habitat, damage to in-stream engineering infrastructure, and re-mobilization of pollutants. Alterations in river hydraulics, sediment transport and stream morphology from specific unsteady events prove challenging to accurately predict and assess. This research quantifies the morphodynamic response of stream beds to unsteady flow events of varying magnitude and duration. For this purpose, a series of experimental runs is conducted in a 0.31 m-wide, 5.0 m-long laboratory sediment transport flume comprised of a well-sorted medium sand. All runs start from flat-bed initial conditions with a given longitudinal slope. The bed is allowed to develop under constant base-flow (antecedent) conditions until equilibrium conditions are reached. For each run a prescribed increase in flow rate for a pre-determined duration is applied to simulate the unsteady flow event. The magnitude of the increase in flow rate and the duration of the event are systematically varied from run to run. In each run measurements of bed morphology are conducted prior to the event (during antecedent flow conditions), at the conclusion of the event, and following a return base-flow (antecedent) conditions. Sediment transport rates are monitored throughout each run. The morphological response and the time-scale of the bed adjustments to unsteady events is quantified. The effect of the magnitude and duration of the flow increase on this increase is evaluated. This study contributes to the development of predictive tools for engineers and hydrologists to better

  1. Soil surfactant stops water repellency and preferential flow paths

    Oostindie, K.; Dekker, L.W.; Wesseling, J.G.; Ritsema, C.J.


    This study reports the effects of a soil surfactant on reduction and prevention of water repellency and preferential flow paths in a sandy soil of a golf course fairway, located at Bosch en Duin near Utrecht, the Netherlands. The golf course is constructed on inland dunes composed of fine sand with

  2. Ground water stratification and delivery of nitrate to an incised stream under varying flow conditions.

    Böhlke, J K; O'Connell, Michael E; Prestegaard, Karen L


    Ground water processes affecting seasonal variations of surface water nitrate concentrations were investigated in an incised first-order stream in an agricultural watershed with a riparian forest in the coastal plain of Maryland. Aquifer characteristics including sediment stratigraphy, geochemistry, and hydraulic properties were examined in combination with chemical and isotopic analyses of ground water, macropore discharge, and stream water. The ground water flow system exhibits vertical stratification of hydraulic properties and redox conditions, with sub-horizontal boundaries that extend beneath the field and adjacent riparian forest. Below the minimum water table position, ground water age gradients indicate low recharge rates (2-5 cm yr(-1)) and long residence times (years to decades), whereas the transient ground water wedge between the maximum and minimum water table positions has a relatively short residence time (months to years), partly because of an upward increase in hydraulic conductivity. Oxygen reduction and denitrification in recharging ground waters are coupled with pyrite oxidation near the minimum water table elevation in a mottled weathering zone in Tertiary marine glauconitic sediments. The incised stream had high nitrate concentrations during high flow conditions when much of the ground water was transmitted rapidly across the riparian zone in a shallow oxic aquifer wedge with abundant outflow macropores, and low nitrate concentrations during low flow conditions when the oxic wedge was smaller and stream discharge was dominated by upwelling from the deeper denitrified parts of the aquifer. Results from this and similar studies illustrate the importance of near-stream geomorphology and subsurface geology as controls of riparian zone function and delivery of nitrate to streams in agricultural watersheds.

  3. Changes in Stream Flow and Their Relationships with Climatic Variations and Anthropogenic Activities in the Poyang Lake Basin, China

    Chaojun Gu


    Full Text Available The Poyang Lake Basin has been suffering from severe water problems such as floods and droughts. This has led to great adverse impacts on local ecosystems and water resource utilization. It is therefore important to understand stream flow changes and their driving factors. In this paper, the dynamics of stream flow and precipitation in the Poyang Lake Basin between 1961 and 2012 were evaluated with the Mann–Kendall test, Theil–Sen approaches, Pettitt test, and Pearson’s correlation. Stream flow was measured at the outlets of five major tributaries of Poyang Lake, while precipitation was recorded by fourteen meteorological stations located within the Poyang Lake Basin. Results showed that annual stream flow of all tributaries and the precipitation over the study area had insignificant (P > 0.1 temporal trends and change points, while significant trends and shifts were found in monthly scale. Stream flow concentration indices (SCI at Waizhou, Meigang, and Wanjiabu stations showed significant (P < 0.05 decreasing trends with change points emerging in 1984 at Waizhou and 1978 at Wanjiabu, while there was no significant temporal trend and change point detected for the precipitation concentration indices (PCI. Correlation analysis indicated that area-average stream flow was closely related to area-average precipitation, but area-average SCI was insignificantly correlated with area-average PCI after change point (1984. El Niño/Southern Oscillation (ENSO had greater impacts on stream flow than other climate indices, and La Niña events played a more important role in stream flow changes than EI Niño. Human activities, particularly in terms of reservoir constructions, largely altered the intra-annual distribution of stream flow but its effects on the amount of stream flow were relatively low. Results of this study provided a useful reference to regional water resource management and the prevention of flood and drought disasters.

  4. Acoustic streaming and thermal instability of flow generated by ultrasound in a cylindrical container

    Green, Adam; Marshall, Jeffrey S.; Ma, Dong; Wu, Junru


    A vertically orientated ultrasonic transducer contained within a closed cylindrical Pyrex tube was used to study the acoustic streaming flow within a cylindrical container. A particle-image velocimetry (PIV) system incorporating fluorescent 1.5 μm seeding particles suspended in a mixture of diethyl-phthalate and ethanol, whose optical index was matched to that of Pyrex, was used to allow for undistorted PIV imaging within the Pyrex tube. Temperature on the end-wall surface and acoustic pressure within the cylinder were measured for different end-wall materials. Variables considered included acoustic absorption and reflection coefficients, ultrasound intensity, container height, and thermal properties of the end-wall material. It was observed that a quasi-steady flow field driven by acoustic streaming is rapidly established within the container, which is typically dominated by a stationary vortex ring with downward flow along the ring axis. After sufficient time this quasi-stationary flow exhibits a thermal instability causing it to transform into a secondary flow state. Different types of secondary flow states were observed, including cases where the flow along the cylinder axis is oriented upward toward the ultrasound transducer and cases where the axial flow changes directions along the cylinder axis.

  5. Interactions between hyporheic flow produced by stream meanders, bars, and dunes

    Stonedahl, Susa H.; Harvey, Judson W.; Packman, Aaron I.


    Stream channel morphology from grain-scale roughness to large meanders drives hyporheic exchange flow. In practice, it is difficult to model hyporheic flow over the wide spectrum of topographic features typically found in rivers. As a result, many studies only characterize isolated exchange processes at a single spatial scale. In this work, we simulated hyporheic flows induced by a range of geomorphic features including meanders, bars and dunes in sand bed streams. Twenty cases were examined with 5 degrees of river meandering. Each meandering river model was run initially without any small topographic features. Models were run again after superimposing only bars and then only dunes, and then run a final time after including all scales of topographic features. This allowed us to investigate the relative importance and interactions between flows induced by different scales of topography. We found that dunes typically contributed more to hyporheic exchange than bars and meanders. Furthermore, our simulations show that the volume of water exchanged and the distributions of hyporheic residence times resulting from various scales of topographic features are close to, but not linearly additive. These findings can potentially be used to develop scaling laws for hyporheic flow that can be widely applied in streams and rivers.

  6. Streaming flow due to a quartz tuning fork oscillating in normal and superfluid 4He

    Duda, D.; La Mantia, M.; Skrbek, L.


    We visualize the streaming flow due to a rapidly oscillating quartz tuning fork, in both normal He I and superfluid He II, by following the flow-induced motions of relatively small particles suspended in the liquid. Over the investigated temperature range, between 1.2 and 2.3 K, at the experimentally probed length scales, the streaming patterns observed in He II appear identical to those seen in He I and are very similar to those reported to occur in water, outside the Stokes boundary layer. The outcome strongly supports the view that, at scales larger than the quantum length scale of the flow, the mean distance between quantized vortices, mechanically forced turbulent coflows of He II behave classically, due to the dynamical locking of the two components of superfluid 4He by the action of the mutual friction force.

  7. E. coli transport to stream water column from bottom sediments to the stream water column in base flow conditions

    Pachepsky, Yakov; Shelton, Daniel; Stocker, Matthew


    E. coli as an indicator bacterium is commonly used to characterize microbiological water quality, to evaluate surface water sources for microbiological impairment, and to assess management practices that lead to the decrease of pathogens and indicator influx in surface water sources for recreation and irrigation. Bottom sediments present a large reservoir of fecal indicator bacteria that are known to be released to water column during high flow events caused by rainstorms and snowmelt. The objective of this work was to see if the influx of E. coli from sediments to water occurs also during base flow periods when groundwater rather than runoff provides the major water input to the stream. The experiment was carried out at the first-order creek in Maryland flowing in the riparian zone in base flow conditions. An inert tracer was released to creek water from the manifold for 5 hours. Streamflow and concentrations of E. coli and tracer were monitored in water 10 m below tracer release location, and at the downstream location at 450 m from the release location. The tracer mass recovered at the downstream location was close to the released tracer mass. We then could directly compare the total numbers of E. coli in volumes of water containing tracer at the upstream (release) location and the downstream location. There was a substantial (3 to 6 times) increase in flow between the upstream and downstream locations as well as the substantial increase in the E. coli total numbers in water (14 to 26 times). The average E. coli influx from the bottom sediment was about 400 cells m-2s-1. Although this value is about 2 to 5 times less than published E. coli release rates during high flow events, it still can substantially change the microbial water quality assessment without any input from animal agriculture or manure application. Interesting research objectives include finding out whether the transport of E. coli from bottom sediment to water column during the base flow periods

  8. Viscous Potential Flow Analysis of Electroaerodynamic Instability of a Liquid Sheet Sprayed with an Air Stream

    Mukesh Kumar Awasthi


    Full Text Available The instability of a thin sheet of viscous and dielectric liquid moving in the same direction as an air stream in the presence of a uniform horizontal electric field has been carried out using viscous potential flow theory. It is observed that aerodynamic-enhanced instability occurs if the Weber number is much less than a critical value related to the ratio of the air and liquid stream velocities, viscosity ratio of two fluids, the electric field, and the dielectric constant values. Liquid viscosity has stabilizing effect in the stability analysis, while air viscosity has destabilizing effect.

  9. Experimental investigation on the near flow field of dual stream nozzles

    Sudhakar, S.; Karthikeyan, N.; Ashwin Kumar, S.


    An experimental investigation was carried out to investigate the effect of beveling of primary nozzle exit in the near field of a dual stream nozzle flow. Two exit geometry configurations of primary stream nozzle viz., (a) circular (b) bevel along with one exit geometry of the secondary stream-circular, were studied. Experiments were carried out at both subsonic and supersonic primary nozzle operating conditions Mp=0.96 and 1.2. The secondary nozzle exit Mach number was maintained at 0.65 and 0.85 respectively to maintain the velocity ratio of 0.7 between the primary and secondary jet. The by-pass ratio for this investigation is maintained at 2.0. Flow visualization using retro-reflective shadowgraph technique was used for the qualitative visualization of the near flow field at the Mach number of 1.2. The mean and turbulent quantities in near flow field were obtained using particle image Velocimetry (2D-PIV). The flow visualization and PIV investigations show significant change in mean and turbulent quantities brought about in the near field due to the beveling of the primary nozzle. PIV results show increase in the potential core length and reduction in turbulence levels in the potential core by the secondary flow regardless of the jet exit geometry. A differential trend is seen in the shear layer growth and the turbulence characteristics between the shorter and longer lips sides of the beveled nozzle. In the dual stream configurations, bevel nozzle shows lower Reynolds stress values than the circular one except in the shorter lip side at the larger downstream locations.

  10. Numerical Simulation of Preferential Flow of Contaminants in Soil


    A simple modeling approach was suggested to simulate preferential transport of water and contaminants in soil.After saturated hydraulic conductivity was interpolated by means of Krige interpolation method or scaling method, and then zoned,the locations where saturated hydraulic conductivity was larger represented regions where preferential flow occurred,because heterogeneity of soil,one of the mechanisms resulting in preferential flow,could be reflected through the difference in saturated hydraulic conductivity.The modeling approach was validated through numerical simulation of contaminant transport in a two-dimensional hypothetical soil profile.The results of the numerical simulation showed that the approach suggested in this study was feasible.

  11. Soil pipe flow tracer experiments: 1. Connectivity and transport characteristics

    Much debate has occurred in catchment hydrology regarding the connectivity of flow paths from upslope areas to catchment outlets. This study was conducted in two catchments, one with three upper branches, in a loess soil with a fragipan that fosters lateral flow and exhibits an extensive distributio...

  12. An evaluation of the relations between flow regime components, stream characteristics, species traits and meta-demographic rates of warmwater stream fishes: Implications for aquatic resource management

    Peterson, James T.; Shea, C.P.


    Fishery biologists are increasingly recognizing the importance of considering the dynamic nature of streams when developing streamflow policies. Such approaches require information on how flow regimes influence the physical environment and how those factors, in turn, affect species-specific demographic rates. A more cost-effective alternative could be the use of dynamic occupancy models to predict how species are likely to respond to changes in flow. To appraise the efficacy of this approach, we evaluated relative support for hypothesized effects of seasonal streamflow components, stream channel characteristics, and fish species traits on local extinction, colonization, and recruitment (meta-demographic rates) of stream fishes. We used 4 years of seasonal fish collection data from 23 streams to fit multistate, multiseason occupancy models for 42 fish species in the lower Flint River Basin, Georgia. Modelling results suggested that meta-demographic rates were influenced by streamflows, particularly short-term (10-day) flows. Flow effects on meta-demographic rates also varied with stream size, channel morphology, and fish species traits. Small-bodied species with generalized life-history characteristics were more resilient to flow variability than large-bodied species with specialized life-history characteristics. Using this approach, we simplified the modelling framework, thereby facilitating the development of dynamic, spatially explicit evaluations of the ecological consequences of water resource development activities over broad geographic areas. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  13. Lagrangian mass-flow investigations of inorganic contaminants in wastewater-impacted streams

    Barber, L.B.; Antweiler, R.C.; Flynn, J.L.; Keefe, S.H.; Kolpin, D.W.; Roth, D.A.; Schnoebelen, D.J.; Taylor, H.E.; Verplanck, P.L.


    Understanding the potential effects of increased reliance on wastewater treatment plant (WWTP) effluents to meet municipal, agricultural, and environmental flow requires an understanding of the complex chemical loading characteristics of the WWTPs and the assimilative capacity of receiving waters. Stream ecosystem effects are linked to proportions of WWTP effluent under low-flow conditions as well as the nature of the effluent chemical mixtures. This study quantifies the loading of 58 inorganic constituents (nutrients to rare earth elements) from WWTP discharges relative to upstream landscape-based sources. Stream assimilation capacity was evaluated by Lagrangian sampling, using flow velocities determined from tracer experiments to track the same parcel of water as it moved downstream. Boulder Creek, Colorado and Fourmile Creek, Iowa, representing two different geologic and hydrologic landscapes, were sampled under low-flow conditions in the summer and spring. One-half of the constituents had greater loads from the WWTP effluents than the upstream drainages, and once introduced into the streams, dilution was the predominant assimilation mechanism. Only ammonium and bismuth had significant decreases in mass load downstream from the WWTPs during all samplings. The link between hydrology and water chemistry inherent in Lagrangian sampling allows quantitative assessment of chemical fate across different landscapes. ?? 2011 American Chemical Society.

  14. Variations in soil detachment rates after wildfire as a function of soil depth, flow properties, and root properties

    Moody, John A.; Nyman, Peter


    Wildfire affects hillslope erosion through increased surface runoff and increased sediment availability, both of which contribute to large post-fire erosion events. Relations between soil detachment rate, soil depth, flow and root properties, and fire impacts are poorly understood and not represented explicitly in commonly used post-fire erosion models. Detachment rates were measured on intact soil cores using a modified tilting flume. The cores were mounted flush with the flume-bed and a measurement was made on the surface of the core. The core was extruded upward, cut off, and another measurement was repeated at a different depth below the original surface of the core. Intact cores were collected from one site burned by the 2010 Fourmile Canyon (FMC) fire in Colorado and from one site burned by the 2010 Pozo fire in California. Each site contained contrasting vegetation and soil types. Additional soil samples were collected alongside the intact cores and were analyzed in the laboratory for soil properties (organic matter, bulk density, particle-size distribution) and for root properties (root density and root-length density). Particle-size distribution and root properties were different between sites, but sites were similar in terms of bulk density and organic matter. Soil detachment rates had similar relations with non-uniform shear stress and non-uniform unit stream power. Detachment rates within single sampling units displayed a relatively weak and inconsistent relation to flow variables. When averaged across all clusters, the detachment rate displayed a linear relation to shear stress, but variability in soil properties meant that the shear stress accounted for only a small proportion of the overall variability in detachment rates (R2 = 0.23; R2 is the coefficient of determination). Detachment rate was related to root-length density in some clusters (R2 values up to 0.91) and unrelated in others (R2 values 2 value improved and the range of exponents became

  15. A millennium-length reconstruction of Bear River stream flow, Utah

    DeRose, R. J.; Bekker, M. F.; Wang, S.-Y.; Buckley, B. M.; Kjelgren, R. K.; Bardsley, T.; Rittenour, T. M.; Allen, E. B.


    The Bear River contributes more water to the eastern Great Basin than any other river system. It is also the most significant source of water for the burgeoning Wasatch Front metropolitan area in northern Utah. Despite its importance for water resources for the region's agricultural, urban, and wildlife needs, our understanding of the variability of Bear River's stream flow derives entirely from the short instrumental record (1943-2010). Here we present a 1200-year calibrated and verified tree-ring reconstruction of stream flow for the Bear River that explains 67% of the variance of the instrumental record over the period from 1943 to 2010. Furthermore, we developed this reconstruction from a species that is not typically used for dendroclimatology, Utah juniper (Juniperus osteosperma). We identify highly significant periodicity in our reconstruction at quasi-decadal (7-8 year), multi-decadal (30 year), and centennial (>50 years) scales. The latter half of the 20th century was found to be the 2nd wettest (∼40-year) period of the past 1200 years, while the first half of the 20th century marked the 4th driest period. The most severe period of reduced stream flow occurred during the Medieval Warm Period (ca. mid-1200s CE) and persisted for ∼70 years. Upper-level circulation anomalies suggest that atmospheric teleconnections originating in the western tropical Pacific are responsible for the delivery of precipitation to the Bear River watershed during the October-December (OND) season of the previous year. The Bear River flow was compared to recent reconstructions of the other tributaries to the Great Salt Lake (GSL) and the GSL level. Implications for water management could be drawn from the observation that the latter half of the 20th century was the 2nd wettest in 1200 years, and that management for future water supply should take into account the stream flow variability over the past millennium.

  16. A Mechanism for Cytoplasmic Streaming: Kinesin-Driven Alignment of Microtubules and Fast Fluid Flows.

    Monteith, Corey E; Brunner, Matthew E; Djagaeva, Inna; Bielecki, Anthony M; Deutsch, Joshua M; Saxton, William M


    The transport of cytoplasmic components can be profoundly affected by hydrodynamics. Cytoplasmic streaming in Drosophila oocytes offers a striking example. Forces on fluid from kinesin-1 are initially directed by a disordered meshwork of microtubules, generating minor slow cytoplasmic flows. Subsequently, to mix incoming nurse cell cytoplasm with ooplasm, a subcortical layer of microtubules forms parallel arrays that support long-range, fast flows. To analyze the streaming mechanism, we combined observations of microtubule and organelle motions with detailed mathematical modeling. In the fast state, microtubules tethered to the cortex form a thin subcortical layer and undergo correlated sinusoidal bending. Organelles moving in flows along the arrays show velocities that are slow near the cortex and fast on the inward side of the subcortical microtubule layer. Starting with fundamental physical principles suggested by qualitative hypotheses, and with published values for microtubule stiffness, kinesin velocity, and cytoplasmic viscosity, we developed a quantitative coupled hydrodynamic model for streaming. The fully detailed mathematical model and its simulations identify key variables that can shift the system between disordered (slow) and ordered (fast) states. Measurements of array curvature, wave period, and the effects of diminished kinesin velocity on flow rates, as well as prior observations on f-actin perturbation, support the model. This establishes a concrete mechanistic framework for the ooplasmic streaming process. The self-organizing fast phase is a result of viscous drag on kinesin-driven cargoes that mediates equal and opposite forces on cytoplasmic fluid and on microtubules whose minus ends are tethered to the cortex. Fluid moves toward plus ends and microtubules are forced backward toward their minus ends, resulting in buckling. Under certain conditions, the buckling microtubules self-organize into parallel bending arrays, guiding varying directions

  17. The effects of human land use on flow regime and water chemistry of headwater streams in the highlands of Chiapas

    Castillo M.M.


    Full Text Available We studied the effects of land use changes on flow regime and water chemistry of headwater streams in the highlands of Chiapas, a region in southern Mexico that has experienced high rates of deforestation in the last decades. Samples for water chemistry were collected and discharge was measured between September 2007 and August 2008 at eight streams that differed in the land uses of their riparian and catchment areas, including streams draining protected forested areas. Streams with high forest cover (>70% in their catchments maintained flow through the year. Streams draining more disturbed catchments exhibited reduced or no flow for 4 − 6 months during the dry season. Nitrate concentrations were lower at streams draining forested catchments while highest concentrations were measured where conventional agriculture covered a high proportion of the catchment and riparian zone. Highest phosphorus concentrations occurred at the catchment where poultry manure was applied as fertilizer. Differences between forest streams and those draining disturbed areas were correlated with the proportion of forest and agriculture in the riparian zone. Variation in stream variables among sampling dates was lower at the forest sites than at the more disturbed study streams. Conversion of forest into agriculture and urban areas is affecting flow regime and increasing nutrient concentrations, although the magnitude of the impacts are influenced by the type of agricultural practices and the alteration of the riparian zone.

  18. Type and timing of stream flow changes in urbanizing watersheds in the Eastern U.S.

    Kristina G. Hopkins


    Full Text Available Abstract Linking the type and timing of hydrologic changes with patterns of urban growth is essential to identifying the underlying mechanisms that drive declines in urban aquatic ecosystems. In six urbanizing watersheds surrounding three U.S. cities (Baltimore, MD, Boston, MA, and Pittsburgh, PA, we reconstructed the history of development patterns since 1900 and assessed the magnitude and timing of stream flow changes during watershed development. Development reconstructions indicated that the majority of watershed development occurred during a period of peak population growth, typically between 1950 and 1970. Stream flow records indicated significant increases in annual frequency of high-flow events in all six watersheds and increases in annual runoff efficiency in five watersheds. Annual development intensity during the peak growth period had the strongest association with the magnitude of changes in high-flow frequency from the pre- to post-development periods. Results suggest the timing of the peak growth period is particularly important to understanding hydrologic changes, because it can set the type of stormwater infrastructure installed within a watershed. In three watersheds there was a rapid (∼10-15 years shift toward more frequent high-flow events, and in four watersheds there was a shift toward higher runoff efficiency. Breakpoint analyses indicated these shifts occurred between 1969 and 1976 for high-flow frequency and between 1962 and 1984 for runoff efficiency. Results indicated that the timing of high-flow changes were mainly driven by the development trajectory of each watershed, whereas the timing of runoff-efficiency changes were driven by a combination of development trajectories and extreme weather events. Our results underscore the need to refine the causes of urban stream degradation to incorporate the impact of gradual versus rapid urbanization on hydrologic changes and aquatic ecosystem function, as well as to

  19. StreamFlow 1.0: an extension to the spatially distributed snow model Alpine3D for hydrological modelling and deterministic stream temperature prediction

    Gallice, Aurélien; Bavay, Mathias; Brauchli, Tristan; Comola, Francesco; Lehning, Michael; Huwald, Hendrik


    Climate change is expected to strongly impact the hydrological and thermal regimes of Alpine rivers within the coming decades. In this context, the development of hydrological models accounting for the specific dynamics of Alpine catchments appears as one of the promising approaches to reduce our uncertainty of future mountain hydrology. This paper describes the improvements brought to StreamFlow, an existing model for hydrological and stream temperature prediction built as an external extension to the physically based snow model Alpine3D. StreamFlow's source code has been entirely written anew, taking advantage of object-oriented programming to significantly improve its structure and ease the implementation of future developments. The source code is now publicly available online, along with a complete documentation. A special emphasis has been put on modularity during the re-implementation of StreamFlow, so that many model aspects can be represented using different alternatives. For example, several options are now available to model the advection of water within the stream. This allows for an easy and fast comparison between different approaches and helps in defining more reliable uncertainty estimates of the model forecasts. In particular, a case study in a Swiss Alpine catchment reveals that the stream temperature predictions are particularly sensitive to the approach used to model the temperature of subsurface flow, a fact which has been poorly reported in the literature to date. Based on the case study, StreamFlow is shown to reproduce hourly mean discharge with a Nash-Sutcliffe efficiency (NSE) of 0.82 and hourly mean temperature with a NSE of 0.78.

  20. A low cost strategy to monitor the expansion and contraction of the flowing stream network in mountainous headwater catchments

    Assendelft, Rick; van Meerveld, Ilja; Seibert, Jan


    Streams are dynamic features in the landscape. The flowing stream network expands and contracts, connects and disconnects in response to rainfall events and seasonal changes in catchment wetness. Sections of the river system that experience these wet and dry cycles are often referred to as temporary streams. Temporary streams are abundant and widely distributed freshwater ecosystems. They account for more than half of the total length of the global stream network, are unique habitats and form important hydrological and ecological links between the uplands and perennial streams. However, temporary streams have been largely unstudied, especially in mountainous headwater catchments. The dynamic character of these systems makes it difficult to monitor them. We describe a low-cost, do-it-yourself strategy to monitor the occurrence of water and flow in temporary streams. We evaluate this strategy in two headwater catchments in Switzerland. The low cost sensor network consists of electrical resistivity sensors, water level switches, temperature sensors and flow sensors. These sensors are connected to Arduino microcontrollers and data loggers, which log the data every 5 minutes. The data from the measurement network are compared with observations (mapping of the temporary stream network) as well as time lapse camera data to evaluate the performance of the sensors. We look at how frequently the output of the sensors (presence and absence of water from the ER and water level data, and flow or no-flow from the flow sensors) corresponds to the observed channel state. This is done for each sensor, per sub-catchment, per precipitation event and per sensor location to determine the best sensor combination to monitor temporary streams in mountainous catchments and in which situation which sensor combination works best. The preliminary results show that the sensors and monitoring network work well. The data from the sensors corresponds with the observations and provides information

  1. Acoustically Induced Streaming Flows near a Model Cod Otolith and their Potential Implications for Fish Hearing

    Kotas, Charlotte W [ORNL; Rogers, Peter [Georgia Institute of Technology; Yoda, Minami [Georgia Institute of Technology


    The ears of fishes are remarkable sensors for the small acoustic disturbances associated with underwater sound. For example, each ear of the Atlantic cod (Gadus morhua) has three dense bony bodies (otoliths) surrounded by fluid and tissue, and detects sounds at frequencies from 30 to 500 Hz. Atlantic cod have also been shown to localize sounds. However, how their ears perform these functions is not fully understood. Steady streaming, or time-independent, flows near a 350% scale model Atlantic cod otolith immersed in a viscous fluid were studied to determine if these fluid flows contain acoustically relevant information that could be detected by the ear s sensory hair cells. The otolith was oscillated sinusoidally at various orientations at frequencies of 8 24 Hz, corresponding to an actual frequency range of 280 830 Hz. Phaselocked particle pathline visualizations of the resulting flows give velocity, vorticity, and rate of strain fields over a single plane of this mainly two-dimensional flow. Although the streaming flows contain acoustically relevant information, the displacements due to these flows are likely too small to explain Atlantic cod hearing abilities near threshold. The results, however, may suggest a possible mechanism for detection of ultrasound in some fish species.

  2. Entropy resistance analyses of a two-stream parallel flow heat exchanger with viscous heating

    Cheng Xue-Tao; Liang Xin-Gang


    Heat exchangers are widely used in industry,and analyses and optimizations of the performance of heat exchangers are important topics.In this paper,we define the concept of entropy resistance based on the entropy generation analyses of a one-dimensional heat transfer process.With this concept,a two-stream parallel flow heat exchanger with viscous heating is analyzed and discussed.It is found that the minimization of entropy resistance always leads to the maximum heat transfer rate for the discussed two-stream parallel flow heat exchanger,while the minimizations of entropy generation rate,entropy generation numbers,and revised entropy generation number do not always.

  3. Split Stream Flow Past a Blunt Trailing Edge with Application to Combustion Instabilities


    woven cotton cheesecloth, a slightly denser muslin cheesecloth, and polyester filter felt. To vary the velocity ratio, honeycomb, mesh, and cloth...good characterization of hydrodynamic instabilities for the case of non -reacting flows is the first step to understand how combustion and of water at room temperature and the average velocity of the two streams. The shedding frequency was non -dimensionalized using a Strouhal number

  4. The contribution of glacier melt to stream flow in the Wind River Range, WY

    Cable, J. M.; Williams, D. G.; Bachman, S. A.


    The Wind River Range (Wyoming) boasts the largest concentration of glaciers in the American Rockies, and together with adjacent mountain ranges is the source of several major river systems in the western US. Declines in the volume of these glaciers associated with recent climate warming are well documented. Such declines of alpine glaciers will reduce the amount of water available for agricultural and domestic use, especially in late summer and fall. The contribution of glacial melt to stream flow remains largely unquantified in many parts of the U.S., particularly in Wyoming. In this study, we estimated the fractional contribution of glacier melt water from Dinwoody Glacier to flow in Dinwoody Creek in the Wind River Range on diurnal, seasonal, and interannual time scales. The stable isotope composition of water from the Dinwoody Creek watershed was determined on spatially and temporally intensive scales in 2007 and 2008. Spatially intensive sampling took place in the summers of both years; water samples were collected from (1) above and below major confluences along Dinwoody Creek, from (2) Dinwoody Glacier, (3) rain water, and (4) snow. Stream samples were collected over the entire melt season using an automated stream sampler placed beside an unimpaired USGS gauging station low in the watershed. Glacial melt contributed significantly to stream flow during periods of peak daily discharge (afternoon) and during late summer peak flow (late-August). In 2008, snow persisted late into the summer, so snowmelt was the main source of streamflow in mid-summer (July). Disappearance of glaciers in this watershed will affect both ecosystem and human water supplies during the late summer period, particularly in years when snowfields do not persist late into the summer.

  5. Artificial intelligence based models for stream-flow forecasting: 2000-2015

    Yaseen, Zaher Mundher; El-shafie, Ahmed; Jaafar, Othman; Afan, Haitham Abdulmohsin; Sayl, Khamis Naba


    The use of Artificial Intelligence (AI) has increased since the middle of the 20th century as seen in its application in a wide range of engineering and science problems. The last two decades, for example, has seen a dramatic increase in the development and application of various types of AI approaches for stream-flow forecasting. Generally speaking, AI has exhibited significant progress in forecasting and modeling non-linear hydrological applications and in capturing the noise complexity in the dataset. This paper explores the state-of-the-art application of AI in stream-flow forecasting, focusing on defining the data-driven of AI, the advantages of complementary models, as well as the literature and their possible future application in modeling and forecasting stream-flow. The review also identifies the major challenges and opportunities for prospective research, including, a new scheme for modeling the inflow, a novel method for preprocessing time series frequency based on Fast Orthogonal Search (FOS) techniques, and Swarm Intelligence (SI) as an optimization approach.


    Shen, Yuandeng; Liu, Yu; Xu, Zhi; Liu, Zhong [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216 (China); Liu, Ying D. [State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190 (China); Chen, P. F. [School of Astronomy and Space Science, Nanjing University, Nanjing 210023 (China); Su, Jiangtao, E-mail: [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)


    We present high-resolution observations of a quiescent solar prominence that consists of a vertical and a horizontal foot encircled by an overlying spine and has ubiquitous counter-streaming mass flows. While the horizontal foot and the spine were connected to the solar surface, the vertical foot was suspended above the solar surface and was supported by a semicircular bubble structure. The bubble first collapsed, then reformed at a similar height, and finally started to oscillate for a long time. We find that the collapse and oscillation of the bubble boundary were tightly associated with a flare-like feature located at the bottom of the bubble. Based on the observational results, we propose that the prominence should be composed of an overlying horizontal spine encircling a low-lying horizontal and vertical foot, in which the horizontal foot consists of shorter field lines running partially along the spine and has ends connected to the solar surface, while the vertical foot consists of piling-up dips due to the sagging of the spine fields and is supported by a bipolar magnetic system formed by parasitic polarities (i.e., the bubble). The upflows in the vertical foot were possibly caused by the magnetic reconnection at the separator between the bubble and the overlying dips, which intruded into the persistent downflow field and formed the picture of counter-streaming mass flows. In addition, the counter-streaming flows in the horizontal foot were possibly caused by the imbalanced pressure at the both ends.

  7. Associations of stream health to altered flow and water temperature in the Sierra Nevada, California

    Carlisle, Daren M.; S. Mark Nelson,; May, Jason


    Alteration of streamflow and thermal conditions may adversely affect lotic invertebrate communities, but few studies have assessed these phenomena using indicators that control for the potentially confounding influence of natural variability. We designed a study to assess how flow and thermal alteration influence stream health – as indicated by the condition of invertebrate communities. We studied thirty streams in the Sierra Nevada, California, that span a wide range of hydrologic modification due to storage reservoirs and hydroelectric diversions. Daily water temperature and streamflows were monitored, and basic chemistry and habitat conditions were characterized when invertebrate communities were sampled. Streamflow alteration, thermal alteration, and invertebrate condition were quantified by predicting site-specific natural expectations using statistical models developed using data from regional reference sites. Monthly flows were typically depleted (relative to natural expectations) during fall, winter, and spring. Most hydrologically altered sites experienced cooled thermal conditions in summer, with mean daily temperatures as much 12 °C below natural expectations. The most influential predictor of invertebrate community condition was the degree of alteration of March flows, which suggests that there are key interactions between hydrological and biological processes during this month in Sierra Nevada streams. Thermal alteration was also an important predictor – particularly at sites with the most severe hydrological alteration.

  8. Iron-rich colloids as carriers of phosphorus in streams: A field-flow fractionation study.

    Baken, Stijn; Regelink, Inge C; Comans, Rob N J; Smolders, Erik; Koopmans, Gerwin F


    Colloidal phosphorus (P) may represent an important fraction of the P in natural waters, but these colloids remain poorly characterized. In this work, we demonstrate the applicability of asymmetric flow field-flow fractionation (AF4) coupled to high resolution ICP-MS for the characterization of low concentrations of P-bearing colloids. Colloids from five streams draining catchments with contrasting properties were characterized by AF4-ICP-MS and by membrane filtration. All streams contain free humic substances (2-3 nm) and Fe-bearing colloids (3-1200 nm). Two soft water streams contain primary Fe oxyhydroxide-humic nanoparticles (3-6 nm) and aggregates thereof (up to 150 nm). In contrast, three harder water streams contain larger aggregates (40-1200 nm) which consist of diverse associations between Fe oxyhydroxides, humic substances, clay minerals, and possibly ferric phosphate minerals. Despite the diversity of colloids encountered in these contrasting streams, P is in most of the samples predominantly associated with Fe-bearing colloids (mostly Fe oxyhydroxides) at molar P:Fe ratios between 0.02 and 1.5. The molar P:Fe ratio of the waters explains the partitioning of P between colloids and truly dissolved species. Waters with a high P:Fe ratio predominantly contain truly dissolved species because the Fe-rich colloids are saturated with P, whereas waters with a low P:Fe ratio mostly contain colloidal P species. Overall, AF4-ICP-MS is a suitable technique to characterize the diverse P-binding colloids in natural waters. Such colloids may increase the mobility or decrease the bioavailability of P, and they therefore need to be considered when addressing the transport and environmental effects of P in catchments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Microbial responses to changes in flow status in temporary headwater streams: a cross-system comparison

    Catherine M Febria


    Full Text Available Microbial communities are responsible for the bulk of biogeochemical processing in temporary headwater streams, yet there is still relatively little known about how community structure and function respond to periodic drying and re-wetting. Moreover, the ability to sample temporary habitats can be a logistical challenge due to the capability to measure and predict the timing, intensity and frequency of wet-dry events. Unsurprisingly, published datasets on microbial community structure and function are limited in scope and temporal resolution and vary widely in the molecular methods applied. We compared environmental and microbial community datasets for permanent and temporary tributaries of two different North American headwater stream systems: Speed River (Ontario, Canada and Parkers Creek (Maryland, USA. We explored whether taxonomic diversity and community composition were altered as a result of flow permanence and compared community composition amongst streams using different 16S microbial community methods (i.e., TRFLP and Illumina MiSeq. Contrary to our hypotheses, and irrespective of method, community composition did not respond strongly to drying. Microbial community composition was related to site rather than drying condition. Additional network analysis on the Parkers Creek dataset showed that community composition shifted only slightly in response to temporary stream drying and microbial co-occurrence data indicated a shift in the central microbial relationships. We compared our results with existing published studies from around the world and found a wide range in community responses to drying. We conclude by proposing three hypotheses that may address contradictory results and, when tested across systems, may expand understanding of the responses of microbial communities in temporary streams to natural and human-induced fluctuations in flow-status and permanence.

  10. Steady streaming: A key mixing mechanism in low-Reynolds-number acinar flows

    Kumar, Haribalan; Tawhai, Merryn H.; Hoffman, Eric A.; Lin, Ching-Long


    Study of mixing is important in understanding transport of submicron sized particles in the acinar region of the lung. In this article, we investigate transport in view of advective mixing utilizing Lagrangian particle tracking techniques: tracer advection, stretch rate and dispersion analysis. The phenomenon of steady streaming in an oscillatory flow is found to hold the key to the origin of kinematic mixing in the alveolus, the alveolar mouth and the alveolated duct. This mechanism provides the common route to folding of material lines and surfaces in any region of the acinar flow, and has no bearing on whether the geometry is expanding or if flow separates within the cavity or not. All analyses consistently indicate a significant decrease in mixing with decreasing Reynolds number (Re). For a given Re, dispersion is found to increase with degree of alveolation, indicating that geometry effects are important. These effects of Re and geometry can also be explained by the streaming mechanism. Based on flow conditions and resultant convective mixing measures, we conclude that significant convective mixing in the duct and within an alveolus could originate only in the first few generations of the acinar tree as a result of nonzero inertia, flow asymmetry, and large Keulegan–Carpenter (KC) number. PMID:21580803

  11. Physical controls and predictability of stream hyporheic flow evaluated with a multiscale model

    Stonedahl, Susa H.; Harvey, Judson W.; Detty, Joel; Aubeneau, Antoine; Packman, Aaron I.


    Improved predictions of hyporheic exchange based on easily measured physical variables are needed to improve assessment of solute transport and reaction processes in watersheds. Here we compare physically based model predictions for an Indiana stream with stream tracer results interpreted using the Transient Storage Model (TSM). We parameterized the physically based, Multiscale Model (MSM) of stream-groundwater interactions with measured stream planform and discharge, stream velocity, streambed hydraulic conductivity and porosity, and topography of the streambed at distinct spatial scales (i.e., ripple, bar, and reach scales). We predicted hyporheic exchange fluxes and hyporheic residence times using the MSM. A Continuous Time Random Walk (CTRW) model was used to convert the MSM output into predictions of in stream solute transport, which we compared with field observations and TSM parameters obtained by fitting solute transport data. MSM simulations indicated that surface-subsurface exchange through smaller topographic features such as ripples was much faster than exchange through larger topographic features such as bars. However, hyporheic exchange varies nonlinearly with groundwater discharge owing to interactions between flows induced at different topographic scales. MSM simulations showed that groundwater discharge significantly decreased both the volume of water entering the subsurface and the time it spent in the subsurface. The MSM also characterized longer timescales of exchange than were observed by the tracer-injection approach. The tracer data, and corresponding TSM fits, were limited by tracer measurement sensitivity and uncertainty in estimates of background tracer concentrations. Our results indicate that rates and patterns of hyporheic exchange are strongly influenced by a continuum of surface-subsurface hydrologic interactions over a wide range of spatial and temporal scales rather than discrete processes.

  12. Gas flow within Martian soil: experiments on granular Knudsen compressors

    Koester, Marc; Kelling, Thorben; Teiser, Jens; Wurm, Gerhard


    Thermal creep efficiently transports gas through Martian soil. To quantify the Martian soil pump we carried out laboratory analog experiments with illuminated granular media at low ambient pressure. We used samples of 1 μm to 5 μm SiO2 (quartz), basalt with a broad size distribution between 63 μm and 125 μm, and JSC-Mars 1A with a size fraction from 125 μm to 250 μm. The mean ambient pressure was varied between 50 Pa and 9000 Pa. Illumination was varied between 100 W/m2 and 6700 W/m2. The experiments confirm strong directed gas flows within granular and dusty soil and local sub-soil pressure variations. We find that Martian soil pumps can be described with existing models of thermal creep for capillaries, using the average grain size and light flux related temperatures.

  13. Streamwater chemistry and flow dynamics along vegetation-soil gradient in a subalpine Abies fabri forest watershed,China

    SHAN Bao-qing; WANG Wei-dong; YIN Cheng-qing


    Streamwater chemistry and spatial flow dynamics from a subalpine Abies fabri forest in an experimental watershed located in the east slope of Gongga Mountain were analyzed to gain insights into the gradient effect of primary community succession on the stream biogeochemical process. Results showed that high sand content(exceeding 80%) and porosity in the soil(exceeding 20% in A horizon and 35% in B horizon), as well as a thick humus layer on the soil surface, made the water exchange quickly in the Huangbengliu(HBL) watershed. Consequently, no surface runoff was observed, and the stream discharge changed rapidly with the daily precipitation. The flow trends of base ions in the stream water were influenced by the Abies fabri succession gradient. Ca2+, HCO3- and SO42- were the dominant anions in the streamwater in this region. A significant difference of Ca2+, HCO3- and SO42- concentration exported between the succession stages in the watershed can be found. But they had the similar temporal change in the stream flow. Ca2+, HCO3- and SO42- showed significantly negative correlations with the daily precipitation and the stream discharge. Concentrations of Cl-, Na+, K+, and Mg2+ were low in all streamwaters monitored and we observed no differences along the Abies fabri succession gradient. Low ratios of Na:(Na+Ca) (range from 0.1 to 0.2) implied cations were from bedrock weathering(internal source process in the soil system) in this region. But, a variance analysis showed there were almost no differences between rainwater and streamwaters for Mg2+, Na+, K+, and Cl- concentrations. This indicated that they might be come from rainfall inputs (external source). We suggest that the highly mobile capacity, rapid water exchange between precipitation and discharge, and long-term export lead to this observed pattern.

  14. Regional regression equations for the estimation of selected monthly low-flow duration and frequency statistics at ungaged sites on streams in New Jersey

    Watson, Kara M.; McHugh, Amy R.


    Regional regression equations were developed for estimating monthly flow-duration and monthly low-flow frequency statistics for ungaged streams in Coastal Plain and non-coastal regions of New Jersey for baseline and current land- and water-use conditions. The equations were developed to estimate 87 different streamflow statistics, which include the monthly 99-, 90-, 85-, 75-, 50-, and 25-percentile flow-durations of the minimum 1-day daily flow; the August–September 99-, 90-, and 75-percentile minimum 1-day daily flow; and the monthly 7-day, 10-year (M7D10Y) low-flow frequency. These 87 streamflow statistics were computed for 41 continuous-record streamflow-gaging stations (streamgages) with 20 or more years of record and 167 low-flow partial-record stations in New Jersey with 10 or more streamflow measurements. The regression analyses used to develop equations to estimate selected streamflow statistics were performed by testing the relation between flow-duration statistics and low-flow frequency statistics for 32 basin characteristics (physical characteristics, land use, surficial geology, and climate) at the 41 streamgages and 167 low-flow partial-record stations. The regression analyses determined drainage area, soil permeability, average April precipitation, average June precipitation, and percent storage (water bodies and wetlands) were the significant explanatory variables for estimating the selected flow-duration and low-flow frequency statistics. Streamflow estimates were computed for two land- and water-use conditions in New Jersey—land- and water-use during the baseline period of record (defined as the years a streamgage had little to no change in development and water use) and current land- and water-use conditions (1989–2008)—for each selected station using data collected through water year 2008. The baseline period of record is representative of a period when the basin was unaffected by change in development. The current period is

  15. Effects of flow intermittency and pharmaceutical exposure on the structure and metabolism of stream biofilms.

    Corcoll, Natàlia; Casellas, Maria; Huerta, Belinda; Guasch, Helena; Acuña, Vicenç; Rodríguez-Mozaz, Sara; Serra-Compte, Albert; Barceló, Damià; Sabater, Sergi


    Increasing concentrations of pharmaceutical compounds occur in many rivers, but their environmental risk remains poorly studied in stream biofilms. Flow intermittency shapes the structure and functions of ecosystems, and may enhance their sensitivity to toxicants. This study evaluates the effects of a long-term exposure of biofilm communities to a mixture of pharmaceutical compounds at environmental concentrations on biofilm bioaccumulation capacity, the structure and metabolic processes of algae and bacteria communities, and how their potential effects were enhanced or not by the occurrence of flow intermittency. To assess the interaction between those two stressors, an experiment with artificial streams was performed. Stream biofilms were exposed to a mixture of pharmaceuticals, as well as to a short period of flow intermittency. Results indicate that biofilms were negatively affected by pharmaceuticals. The algal biomass and taxa richness decreased and unicellular green algae relatively increased. The structure of the bacterial (based on denaturing gradient gel electrophoresis of amplified 16S rRNA genes) changed and showed a reduction of the operational taxonomic units (OTUs) richness. Exposed biofilms showed higher rates of metabolic processes, such as primary production and community respiration, attributed to pharmaceuticals stimulated an increase of green algae and heterotrophs, respectively. Flow intermittency modulated the effects of chemicals on natural communities. The algal community became more sensitive to short-term exposure of pharmaceuticals (lower EC50 value) when exposed to water intermittency, indicating cumulative effects between the two assessed stressors. In contrast to algae, the bacterial community became less sensitive to short-term exposure of pharmaceuticals (higher EC50) when exposed to water intermittency, indicating co-tolerance phenomena. According to the observed effects, the environmental risk of pharmaceuticals in nature is high

  16. Experimental observations and modeling of ponding and overland flow in flat, permeable soil fields

    Appels, Willemijn; Bogaart, Patrick; van der Zee, Sjoerd


    In flat well-drained agricultural terrain, overland flow is a relatively rare phenomenon, yet still a potentially important driver of sediment and nutrient transport. Under these conditions, periods of intense rainfall, shallow groundwater dynamics and local combinations of meso- and microtopography control whether water in ponds will become connected to streams and ditches. Combining overland flow measurements at agricultural fields with a new modeling approach, we explored: (i) what rainfall conditions relate to overland flow and (ii) how does flow route connectivity develop for various types of runoff generation and meso/microtopography? For this purpose, we assessed overland flow at two field sites in flat, lowland catchments in the sandy part of the Netherlands and developed a dynamic model (FAST-runoff) to simulate redistribution of water over a heterogeneous surface with infiltration and soil water storage. Experimentally, it appeared that most overland flow occurred as saturation excess runoff during long wet periods, though infiltration excess runoff generation may have played a role during snowmelt periods that generated small amounts of runoff. For both fields, the contributing area during the saturation excess events was large and flow paths long, irrespective of the profoundly different microtopographies. We explored this behaviour with our FAST-Runoff model and found that under saturation excess conditions, mesotopographic features, such as natural depressions or those caused by tillage, gain importance at the expense of the spatial organization of microtopography. The surface topographies of our experimental fields were equal in terms of standard topographic analytical measures such as Curvature, Convergence Index, and Topographic Wetness Index. However, the fields could be distinguished when analysed with a quantitative indicator of flow for hydrological connectivity. Also, the fields had different dynamics related to the runoff generating mechanism

  17. Coordinating Mitigation Strategies for Meeting In-Stream Flow Requirements in the Skagit River Basin, WA

    Padowski, J.; Yang, Q.; Brady, M.; Jessup, E.; Yoder, J.


    In 2013, the Washington State Supreme Court ruled against a 2001 amendment that set aside groundwater reservations for development within the Skagit River Basin (Swinomish Indian Tribal Community v. Washington State Department of Ecology). As a consequence, hundreds of properties no longer have a secure, uninterruptible water right and must be fully mitigated to offset their impacts on minimum in-stream flows. To date, no solutions have been amenable to the private, tribal and government parties involved. The objective of this study is to identify implementable, alternative water mitigation strategies for meeting minimum in-stream flow requirements while providing non-interruptible water to 455 property owners without legal water rights in the Skagit Basin. Three strategies of interest to all parties involved were considered: 1) streamflow augmentation from small-gauge municipal pipes, or trucked water deliveries for either 2) direct household use or 3) streamflow augmentation. Each mitigation strategy was assessed under two different demand scenarios and five augmentation points along 19 sub-watershed (HUC12) stream reaches. Results indicate that water piped for streamflow augmentation could provide mitigation at a cost of <10,000 per household for 20 - 60% of the properties in question, but a similar approach could be up to twenty times more expensive for those remaining properties in basins furthest from existing municipal systems. Trucked water costs also increase for upper basin properties, but over a 20-year period are still less expensive for basins where piped water costs would be high (e.g., 100,000 for trucking vs. $200,000 for piped water). This work suggests that coordination with municipal water systems to offset in-stream flow reductions, in combination with strategic mobile water delivery, could provide mitigation solutions within the Skagit Basin that may satisfy concerned parties.

  18. Morphological divergence and flow-induced phenotypic plasticity in a native fish from anthropogenically altered stream habitats.

    Franssen, Nathan R; Stewart, Laura K; Schaefer, Jacob F


    Understanding population-level responses to human-induced changes to habitats can elucidate the evolutionary consequences of rapid habitat alteration. Reservoirs constructed on streams expose stream fishes to novel selective pressures in these habitats. Assessing the drivers of trait divergence facilitated by these habitats will help identify evolutionary and ecological consequences of reservoir habitats. We tested for morphological divergence in a stream fish that occupies both stream and reservoir habitats. To assess contributions of genetic-level differences and phenotypic plasticity induced by flow variation, we spawned and reared individuals from both habitats types in flow and no flow conditions. Body shape significantly and consistently diverged in reservoir habitats compared with streams; individuals from reservoirs were shallower bodied with smaller heads compared with individuals from streams. Significant population-level differences in morphology persisted in offspring but morphological variation compared with field-collected individuals was limited to the head region. Populations demonstrated dissimilar flow-induced phenotypic plasticity when reared under flow, but phenotypic plasticity in response to flow variation was an unlikely explanation for observed phenotypic divergence in the field. Our results, together with previous investigations, suggest the environmental conditions currently thought to drive morphological change in reservoirs (i.e., predation and flow regimes) may not be the sole drivers of phenotypic change.

  19. Estimating peak-flow frequency statistics for selected gaged and ungaged sites in naturally flowing streams and rivers in Idaho

    Wood, Molly S.; Fosness, Ryan L.; Skinner, Kenneth D.; Veilleux, Andrea G.


    The U.S. Geological Survey, in cooperation with the Idaho Transportation Department, updated regional regression equations to estimate peak-flow statistics at ungaged sites on Idaho streams using recent streamflow (flow) data and new statistical techniques. Peak-flow statistics with 80-, 67-, 50-, 43-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (1.25-, 1.50-, 2.00-, 2.33-, 5.00-, 10.0-, 25.0-, 50.0-, 100-, 200-, and 500-year recurrence intervals, respectively) were estimated for 192 streamgages in Idaho and bordering States with at least 10 years of annual peak-flow record through water year 2013. The streamgages were selected from drainage basins with little or no flow diversion or regulation. The peak-flow statistics were estimated by fitting a log-Pearson type III distribution to records of annual peak flows and applying two additional statistical methods: (1) the Expected Moments Algorithm to help describe uncertainty in annual peak flows and to better represent missing and historical record; and (2) the generalized Multiple Grubbs Beck Test to screen out potentially influential low outliers and to better fit the upper end of the peak-flow distribution. Additionally, a new regional skew was estimated for the Pacific Northwest and used to weight at-station skew at most streamgages. The streamgages were grouped into six regions (numbered 1_2, 3, 4, 5, 6_8, and 7, to maintain consistency in region numbering with a previous study), and the estimated peak-flow statistics were related to basin and climatic characteristics to develop regional regression equations using a generalized least squares procedure. Four out of 24 evaluated basin and climatic characteristics were selected for use in the final regional peak-flow regression equations.Overall, the standard error of prediction for the regional peak-flow regression equations ranged from 22 to 132 percent. Among all regions, regression model fit was best for region 4 in west

  20. Root-soil air gap and resistance to water flow at the soil-root interface of Robinia pseudoacacia.

    Liu, X P; Zhang, W J; Wang, X Y; Cai, Y J; Chang, J G


    During periods of water deficit, growing roots may shrink, retaining only partial contact with the soil. In this study, known mathematical models were used to calculate the root-soil air gap and water flow resistance at the soil-root interface, respectively, of Robinia pseudoacacia L. under different water conditions. Using a digital camera, the root-soil air gap of R. pseudoacacia was investigated in a root growth chamber; this root-soil air gap and the model-inferred water flow resistance at the soil-root interface were compared with predictions based on a separate outdoor experiment. The results indicated progressively greater root shrinkage and loss of root-soil contact with decreasing soil water potential. The average widths of the root-soil air gap for R. pseudoacacia in open fields and in the root growth chamber were 0.24 and 0.39 mm, respectively. The resistance to water flow at the soil-root interface in both environments increased with decreasing soil water potential. Stepwise regression analysis demonstrated that soil water potential and soil temperature were the best predictors of variation in the root-soil air gap. A combination of soil water potential, soil temperature, root-air water potential difference and soil-root water potential difference best predicted the resistance to water flow at the soil-root interface.

  1. Roll/streak Structure Instability Induced by Free-stream Turbulence in Couette Flow

    Farrell, Brian; Ioannou, Petros; Nikolaidis, Marios


    Statistical state dynamics (SSD) provides a new perspective for studying mechanisms underlying turbulence in shear flow including instabilities which arise intrinsically from interaction between coherent and incoherent components of the turbulence. Implementations of SSD in the form of a closure at second order is used in this work to analyze the instability emergent from the statistical interaction between coherent perturbations of roll/streak form and the incoherent free-stream turbulence in a minimal channel configuration of Couette flow. By perturbing the nonlinear SSD dynamics a new manifold of stable modes with roll/streak structure is shown to exist in the presence of small amplitude free-stream turbulence. With increase in a parameter controlling the free-stream turbulence energy, a member of this set of stable roll/streak structures is destabilized at a bifurcation and the associated roll/streak eigenmode is found to equilibrate at finite amplitude. The bifurcation structure predicted by the SSD roll/streak instability is reflected in both a closely related quasi-linear dynamical system, referred to as the restricted non-linear (RNL) system, and in DNS. This correspondence is further verified using ensemble implementations of the RNL and DNS systems.

  2. Acoustic streaming in swirling flow and the Ranque-Hilsch /vortex-tube/ effect

    Kurosaka, M.


    The Ranque-Hilsch effect, observed in swirling flow within a single tube, is a spontaneous separation of total temperature, with the colder stream near the tube center line and the hotter air near its periphery. Despite its simplicity, the mechanism of the Ranque-Hilsch effect has been a matter of long-standing dispute. Analysis and experiment are used to demonstrate that the acoustic streaming induced by orderly disturbances within the swirling flow is, to a substantial degree, a cause of the Ranque-Hilsch effect. The analysis predicts that the streaming induced by the pure tone, a spinning wave corresponding to the first tangential mode, deforms the base Rankine vortex into a forced vortex, resulting in total temperature separation in the radial direction. This is confirmed by experiments, where, in the Ranque-Hilsch tube of uniflow arrangement, acoustic suppressors of organ-pipe type are installed, tuned to the discrete frequency of the first tangential mode, attenuate its amplitude, and it is shown that this does indeed reduce the total temperature separation.

  3. FastFlow: Efficient Parallel Streaming Applications on Multi-core

    Aldinucci, Marco; Meneghin, Massimiliano


    Shared memory multiprocessors come back to popularity thanks to rapid spreading of commodity multi-core architectures. As ever, shared memory programs are fairly easy to write and quite hard to optimise; providing multi-core programmers with optimising tools and programming frameworks is a nowadays challenge. Few efforts have been done to support effective streaming applications on these architectures. In this paper we introduce FastFlow, a low-level programming framework based on lock-free queues explicitly designed to support high-level languages for streaming applications. We compare FastFlow with state-of-the-art programming frameworks such as Cilk, OpenMP, and Intel TBB. We experimentally demonstrate that FastFlow is always more efficient than all of them in a set of micro-benchmarks and on a real world application; the speedup edge of FastFlow over other solutions might be bold for fine grain tasks, as an example +35% on OpenMP, +226% on Cilk, +96% on TBB for the alignment of protein P01111 against UniP...

  4. Use of an integrated flow model to estimate ecologically relevant hydrologic characteristics at stream biomonitoring sites

    Kennen, J.G.; Kauffman, L.J.; Ayers, M.A.; Wolock, D.M.; Colarullo, S.J.


    We developed an integrated hydroecological model to provide a comprehensive set of hydrologic variables representing five major components of the flow regime at 856 aquatic-invertebrate monitoring sites in New Jersey. The hydroecological model simulates streamflow by routing water that moves overland and through the subsurface from atmospheric delivery to the watershed outlet. Snow accumulation and melt, evapotranspiration, precipitation, withdrawals, discharges, pervious- and impervious-area runoff, and lake storage were accounted for in the water balance. We generated more than 78 flow variables, which describe the frequency, magnitude, duration, rate of change, and timing of flow events. Highly correlated variables were filtered by principal component analysis to obtain a non-redundant subset of variables that explain the majority of the variation in the complete set. This subset of variables was used to evaluate the effect of changes in the flow regime on aquatic-invertebrate assemblage structure at 856 biomonitoring sites. We used non-metric multidimensional scaling (NMS) to evaluate variation in aquatic-invertebrate assemblage structure across a disturbance gradient. We employed multiple linear regression (MLR) analysis to build a series of MLR models that identify the most important environmental and hydrologic variables driving the differences in the aquatic-invertebrate assemblages across the disturbance gradient. The first axis of NMS ordination was significantly related to many hydrologic, habitat, and land-use/land-cover variables, including the average number of annual storms producing runoff, ratio of 25-75% exceedance flow (flashiness), diversity of natural stream substrate, and the percentage of forested land near the stream channel (forest buffer). Modifications in the hydrologic regime as the result of changes in watershed land use appear to promote the retention of highly tolerant aquatic species; in contrast, species that are sensitive to

  5. Carbon black retention in saturated natural soils: Effects of flow conditions, soil surface roughness and soil organic matter.

    Lohwacharin, J; Takizawa, S; Punyapalakul, P


    We evaluated factors affecting the transport, retention, and re-entrainment of carbon black nanoparticles (nCBs) in two saturated natural soils under different flow conditions and input concentrations using the two-site transport model and Kelvin probe force microscopy (KPFM). Soil organic matter (SOM) was found to create unfavorable conditions for the retention. Despite an increased flow velocity, the relative stability of the estimated maximum retention capacity in soils may suggest that flow-induced shear stress forces were insufficient to detach nCB. The KPFM observation revealed that nCBs were retained at the grain boundary and on surface roughness, which brought about substantial discrepancy between theoretically-derived attachment efficiency factors and the ones obtained by the experiments using the two-site transport model. Thus, decreasing ionic strength and increasing solution pH caused re-entrainment of only a small fraction of retained nCB in the soil columns.

  6. Superamphiphobic Silicon-Nanowire-Embedded Microsystem and In-Contact Flow Performance of Gas and Liquid Streams.

    Ko, Dong-Hyeon; Ren, Wurong; Kim, Jin-Oh; Wang, Jun; Wang, Hao; Sharma, Siddharth; Faustini, Marco; Kim, Dong-Pyo


    Gas and liquid streams are invariably separated either by a solid wall or by a membrane for heat or mass transfer between the gas and liquid streams. Without the separating wall, the gas phase is present as bubbles in liquid or, in a microsystem, as gas plugs between slugs of liquid. Continuous and direct contact between the two moving streams of gas and liquid is quite an efficient way of achieving heat or mass transfer between the two phases. Here, we report a silicon nanowire built-in microsystem in which a liquid stream flows in contact with an underlying gas stream. The upper liquid stream does not penetrate into the lower gas stream due to the superamphiphobic nature of the silicon nanowires built into the bottom wall, thereby preserving the integrity of continuous gas and liquid streams, although they are flowing in contact. Due to the superamphiphobic nature of silicon nanowires, the microsystem provides the best possible interfacial mass transfer known to date between flowing gas and liquid phases, which can achieve excellent chemical performance in two-phase organic syntheses.

  7. The direct and indirect effects of watershed land use and soil type on stream water metal concentrations

    Taka, M.; Aalto, J.; Virkanen, J.; Luoto, M.


    Identifying the factors controlling stream water pollutants is challenged by the diversity of potential sources, pathways, and processes. This study tests the effects of watershed characteristics on stream water metal concentrations across environmental gradients. By using an extensive data set of 83 watersheds in southern Finland and structural equation modeling (SEM), the direct and indirect effects of land use and soil type on metal concentrations were explored. Both land use and soil type resulted in statistically significant direct effects on metals; for example, land use was found to control dissolved metal concentrations, whereas soil type had the strongest links for total metal concentrations. The consideration of indirect correlation further strengthened the effects of soil type up to 50%, thus suggesting the dominant role of soil across land use intensities. Moreover, the results indicate that modified landscapes mediate the effect of natural soil processes in controlling stream metal concentrations. This work highlights the benefits of structural equation model framework, as the underlying paths for water quality are more likely to be identified, compared to traditional regression methods. Thus, the implementation of SEM on water quality studies is highly encouraged.

  8. Flow under standing waves Part 1. Shear stress distribution, energy flux and steady streaming

    Gislason, Kjartan; Fredsøe, Jørgen; Deigaard, Rolf


    The conditions for energy flux, momentum flux and the resulting streaming velocity are analysed for standing waves formed in front of a fully reflecting wall. The exchange of energy between the outer wave motion and the near bed oscillatory boundary layer is considered, determining the horizontal...... energy flux inside and outside the boundary layer. The momentum balance, the mean shear stress and the resulting time averaged streaming velocities are determined. For a laminar bed boundary layer the analysis of the wave drift gives results similar to the original work of Longuet-Higgins from 1953....... The work is extended to turbulent bed boundary layers by application of a numerical model. The similarities and differences between laminar and turbulent flow conditions are discussed, and quantitative results for the magnitude of the mean shear stress and drift velocity are presented. Full two...

  9. Burst intensification by singularity emitting radiation in multi-stream flows

    Pirozhkov, A S; Pikuz, T A; Faenov, A Ya; Ogura, K; Hayashi, Y; Kotaki, H; Ragozin, E N; Neely, D; Kiriyama, H; Koga, J K; Fukuda, Y; Sagisaka, A; Nishikino, M; Imazono, T; Hasegawa, N; Kawachi, T; Bolton, P R; Daido, H; Kato, Y; Kondo, K; Bulanov, S V; Kando, M


    In various media the elementary components can emit traveling waves such as electromagnetic, gravitational or acoustic types. If these elementary emitters are synchronized, the resulting emission is coherent. Moreover, the faster the emitters approach an observer, the more intense and directional their apparent emission is, with associated frequency increase. Multi-stream flows ubiquitously occur in media (such as with shock waves and jets in astrophysical and laboratory plasmas) and produce fast moving density singularities, where high concentration and synchronism can bring constructive interference. However, a singularity emitting such characteristic coherent radiation has not been demonstrated yet. We show this general phenomenon in laser-driven relativistic plasma, which is an ideal medium for realizing these effects in the laboratory under controllable conditions. Our experiments and simulations reveal bright coherent soft x-ray radiation from nanoscale electron density singularities in multi-stream pla...

  10. The Effects of the Impedance of the Flow Source on the Design of Tidal Stream Generators

    Salter, S.


    The maximum performance of a wind turbine is set by the well-known Betz limit. If the designer of a wind turbine uses too fast a rotation, too large a blade chord or too high an angle of blade pitch, the air flow can take an easier path over or around the rotor. Most estimates of the tidal stream resource use equations borrowed from wind and would be reasonably accurate for a single unit. But water cannot flow through the seabed or over rotors which reach to the surface. If contra-rotating, vertical-axis turbines with a rectangular flow-window are placed close to one another and reach from the surface close to the seabed, the leakage path is blocked and they become more like turbines in a closed duct. Instead of an equation with area times velocity-cubed we should use the first power of volume flow rate though the rotor times the pressure difference across it. A long channel with a rough bed will already be losing lots of energy and will behave more like a high impedance flow. Attempts to block it with closely-packed turbines will increase the head across the turbines with only a small effect on flow rate. The same thing will occur if a close-packed line of turbines is built out to sea from a headland. It is necessary to understand the impedance of the flow source all the way out to mid-ocean. In deep seas where the current velocities at the seabed are too slow to disturb the ooze the friction coefficients will be similar to those of gloss paint, perhaps 0.0025. But the higher velocities in shallow water will remove ooze and quite large sediments leaving rough, bare rock and leading to higher friction-coefficients. Energy dissipation will be set by the higher friction coefficients and the cube of the higher velocities. The presence of turbines will reduce seabed losses and about one third of the present loss can be converted to electricity. The velocity reduction would be about 10%. In many sites the energy output will be far higher than the wind turbine equations

  11. Identifying Coherent Structures in a 3-Stream Supersonic Jet Flow using Time-Resolved Schlieren Imaging

    Tenney, Andrew; Coleman, Thomas; Berry, Matthew; Magstadt, Andy; Gogineni, Sivaram; Kiel, Barry


    Shock cells and large scale structures present in a three-stream non-axisymmetric jet are studied both qualitatively and quantitatively. Large Eddy Simulation is utilized first to gain an understanding of the underlying physics of the flow and direct the focus of the physical experiment. The flow in the experiment is visualized using long exposure Schlieren photography, with time resolved Schlieren photography also a possibility. Velocity derivative diagnostics are calculated from the grey-scale Schlieren images are analyzed using continuous wavelet transforms. Pressure signals are also captured in the near-field of the jet to correlate with the velocity derivative diagnostics and assist in unraveling this complex flow. We acknowledge the support of AFRL through an SBIR grant.

  12. The preparation of calcium superoxide in a flowing gas stream and fluidized bed

    Wood, P. C.; Ballou, E. V.; Spitze, L. A.; Wydeven, T.


    Superoxides can be used as sources of chemically stored oxygen in emergency breathing apparatus. The work reported here describes the use of a low-pressure nitrogen gas sweep through the reactant bed, for temperature control and water vapor removal. For a given set of gas temperature, bed thickness, and reaction time values, the highest purity calcium superoxide, Ca(O2)2, was obtained at the highest space velocity of the nitrogen gas sweep. The purity of the product was further increased by flow conditions that resulted in the fluidization of the reactant bed. However, scale-up of the low-pressure fluidized bed process was limited to the formation of agglomerates of reactant particles, which hindered thermal control by the flowing gas stream. A radiofrequency flow discharge inside the reaction chamber prevented agglomeration, presumably by dissipation of the static charges on the fluidized particles.

  13. Formation and evolution of a pair of collisionless shocks in counter-streaming flows

    Yuan, Dawei; Li, Yutong; Liu, Meng; Zhong, Jiayong; Zhu, Baojun; Li, Yanfei; Wei, Huigang; Han, Bo; Pei, Xiaoxing; Zhao, Jiarui; Li, Fang; Zhang, Zhe; Liang, Guiyun; Wang, Feilu; Weng, Suming; Li, Yingjun; Jiang, Shaoen; Du, Kai; Ding, Yongkun; Zhu, Baoqiang; Zhu, Jianqiang; Zhao, Gang; Zhang, Jie


    A pair of collisionless shocks that propagate in the opposite directions are firstly observed in the interactions of laser-produced counter-streaming flows. The flows are generated by irradiating a pair of opposing copper foils with eight laser beams at the Shenguang-II (SG-II) laser facility. The experimental results indicate that the excited shocks are collisionless and electrostatic, in good agreement with the theoretical model of electrostatic shock. The particle-in-cell (PIC) simulations verify that a strong electrostatic field growing from the interaction region contributes to the shocks formation. The evolution is driven by the thermal pressure gradient between the upstream and the downstream. Theoretical analysis indicates that the strength of the shocks is enhanced with the decreasing density ratio during both flows interpenetration. The positive feedback can offset the shock decay process. This is probable the main reason why the electrostatic shocks can keep stable for a longer time in our experiment. PMID:28266497

  14. Methods for estimating selected low-flow frequency statistics for unregulated streams in Kentucky

    Martin, Gary R.; Arihood, Leslie D.


    This report provides estimates of, and presents methods for estimating, selected low-flow frequency statistics for unregulated streams in Kentucky including the 30-day mean low flows for recurrence intervals of 2 and 5 years (30Q2 and 30Q5) and the 7-day mean low flows for recurrence intervals of 5, 10, and 20 years (7Q2, 7Q10, and 7Q20). Estimates of these statistics are provided for 121 U.S. Geological Survey streamflow-gaging stations with data through the 2006 climate year, which is the 12-month period ending March 31 of each year. Data were screened to identify the periods of homogeneous, unregulated flows for use in the analyses. Logistic-regression equations are presented for estimating the annual probability of the selected low-flow frequency statistics being equal to zero. Weighted-least-squares regression equations were developed for estimating the magnitude of the nonzero 30Q2, 30Q5, 7Q2, 7Q10, and 7Q20 low flows. Three low-flow regions were defined for estimating the 7-day low-flow frequency statistics. The explicit explanatory variables in the regression equations include total drainage area and the mapped streamflow-variability index measured from a revised statewide coverage of this characteristic. The percentage of the station low-flow statistics correctly classified as zero or nonzero by use of the logistic-regression equations ranged from 87.5 to 93.8 percent. The average standard errors of prediction of the weighted-least-squares regression equations ranged from 108 to 226 percent. The 30Q2 regression equations have the smallest standard errors of prediction, and the 7Q20 regression equations have the largest standard errors of prediction. The regression equations are applicable only to stream sites with low flows unaffected by regulation from reservoirs and local diversions of flow and to drainage basins in specified ranges of basin characteristics. Caution is advised when applying the equations for basins with characteristics near the

  15. The impact of water-rock interaction and vegetation on calcium isotope fractionation in soil- and stream waters of a small, forested catchment (the Strengbach case)

    Cenki-Tok, B.; Chabaux, F.; Lemarchand, D.; Schmitt, A.-D.; Pierret, M.-C.; Viville, D.; Bagard, M.-L.; Stille, P.


    This study aims to constrain the factors controlling the calcium isotopic compositions in surface waters, especially the respective role of vegetation and water-rock interactions on Ca isotope fractionation in a continental forested ecosystem. The approach is to follow changes in space and time of the isotopic composition and concentration of Ca along its pathway through the hydro-geochemical reservoirs from atmospheric deposits to the outlet of the watershed via throughfalls, percolating soil solutions and springs. The study is focused on the Strengbach catchment, a small forested watershed located in the northeast of France in the Vosges mountains. The δ 44/40Ca values of springs, brooks and stream waters from the catchment are comparable to those of continental rivers and fluctuate between 0.17 and 0.87‰. Soil solutions, however, are significantly depleted in lighter isotopes (δ 44/40Ca: 1.00-1.47‰), whereas vegetation is strongly enriched (δ 44/40Ca: -0.48‰ to +0.19‰). These results highlight that vegetation is a major factor controlling the calcium isotopic composition of soil solutions, with depletion in "light" calcium in the soil solutions from deeper parts of the soil compartments due to preferential 40Ca uptake by the plants rootsystem. However, mass balance calculations require the contribution of an additional Ca flux into the soil solutions most probably associated with water-rock interactions. The stream waters are marked by a seasonal variation of their δ 44/40Ca, with low δ 44/40Ca in winter and high δ 44/40Ca in spring, summer and autumn. For some springs, nourishing the streamlet, a decrease of the δ 44/40Ca value is observed when the discharge of the spring increases, with, in addition, a clear covariation between the δ 44/40Ca and corresponding H 4SiO 4 concentrations: high δ 44/40Ca values and low H 4SiO 4 concentrations at high discharge; low δ 44/40Ca values and high H 4SiO 4 concentrations at low discharge. These data imply

  16. Active subglacial lakes and channelized water flow beneath the Kamb Ice Stream

    Kim, Byeong-Hoon; Lee, Choon-Ki; Seo, Ki-Weon; Lee, Won Sang; Scambos, Ted


    We identify two previously unknown subglacial lakes beneath the stagnated trunk of the Kamb Ice Stream (KIS). Rapid fill-drain hydrologic events over several months are inferred from surface height changes measured by CryoSat-2 altimetry and indicate that the lakes are probably connected by a subglacial drainage network, whose structure is inferred from the regional hydraulic potential and probably links the lakes. The sequential fill-drain behavior of the subglacial lakes and concurrent rapid thinning in a channel-like topographic feature near the grounding line implies that the subglacial water repeatedly flows from the region above the trunk to the KIS grounding line and out beneath the Ross Ice Shelf. Ice shelf elevation near the hypothesized outlet is observed to decrease slowly during the study period. Our finding supports a previously published conceptual model of the KIS shutdown stemming from a transition from distributed flow to well-drained channelized flow of subglacial water. However, a water-piracy hypothesis in which the KIS subglacial water system is being starved by drainage in adjacent ice streams is also supported by the fact that the degree of KIS trunk subglacial lake activity is relatively weaker than those of the upstream lakes.




    Full Text Available Hydraulic effects on the vegetation behavior and on its habitat region against flood flow in the urban streams were analysed in this paper. Vegetation behavior was classified into stable, recovered, damaged and swept away stages. Criteria between recovered and damaged status were determined by the bending angle of the aquatic plants. Aquatic plants whose bending angle is lower than 30~50 degree is recovered, but they were damaged and cannot be recovered when the bending angle is higher than 30~50 degree. Phragmites japonica was inhabited in the hydraulic condition of high Froude number which shows that it was inhabited in the upstream reaches. Phragmites communis was inhabited in the relatively low Froude number compared with Phragmites japonica. This shows that it was inhabited in the downstream reaches. Persicaria blumei was found in the relatively wide range of flow velocity and flow depth, which shows that it was inhabited in the middle and downstream reaches. Criterion on the vegetation behavior of Persicaria thunbergii was not clear, which implies that it may be affected by the flow turbulence rather than flow velocity and flow depth.

  18. A novel flow-based procedure for automation of respirometric assays in soils.

    Silva, Claudineia R; Oliveira, Eliezer; Zagatto, Elias A G; Henriquez, Camelia


    A flow-based strategy involving a gas-diffusion sampling probe was proposed for evaluating the respiration rate in soils. The amount of CO2 collected after a pre-defined time interval was proportional to the free CO2 released by the soil ecosystem. The 500-mL incubation flasks typically used for soil respirometric assays were adapted and a special cover was designed for connecting a tubular gas diffusion membrane, a fan, and a septum for adding the CO2(g) standards required for calibration. The method relied on the pH-dependent absorbance variations resulting from the CO2 collection. A 1.3mmolL(-1) bromothymol blue solution (pH 7.0) acted as both acceptor and carrier streams. In order to widen the dynamical working range to 0.003-0.2mmol CO2, two analytical curves were obtained, each related to a different time interval for the CO2 collection. Kinetic curves related to CO2 release by the soil samples were straightforwardly attained. Repeatability and detection limit were estimated as 2.0% and 0.001mmol CO2 (n=10), and accuracy was assessed in relation to a recommended titrimetric procedure.

  19. Surface flow types, near-bed hydraulics and the distribution of stream macroinvertebrates

    M. A. Reid


    Full Text Available Spatial variation in hydraulic conditions in streams often results in distinct water surface patterns, or surface flow types. Visual assessments of the distribution of surface flow types have been used to provide rapid assessment of the habitat heterogeneity. The efficacy of this approach is predicated on the notion that surface flow types consistently represent a distinct suite of hydraulic conditions with biological relevance. This study tested this notion, asking three specific questions. First, do surface flow types provide a characterisation of physical habitat that is relevant to macroinvertebrates? Second, how well do near-bed hydraulic conditions explain macroinvertebrate distributions? Third, what components of near-bed hydraulic conditions exert the strongest influence on macroinvertebrate distributions?

    Results show that hydraulic conditions (incorporating direct measurements of near-bed velocity and turbulence in three dimensions and substratum character (incorporating estimates of particle size distribution, and biofilm and macrophyte cover within each surface flow type were largely distinct and that macroinvertebrate assemblages differed across flow types in taxon richness and assemblage composition, thus supporting the notion that rapid assessments of surface flow type distributions provide biologically relevant information.

    Macroinvertebrate assemblages were most strongly correlated with water depth, size of a flow type patch, near-bed velocity in the downstream direction, turbulence in the transverse direction, % pebble, % sand, % silt and clay and macrophyte cover. This study suggests that surface flow type mapping provides an assessment of physical habitat that is relevant to macroinvertebrates. The strong relationship detected between macroinvertebrate assemblages and transverse turbulence also highlights the value of directly measuring near-bed hydraulics. Further investigations are required to test the

  20. Surface flow types, near-bed hydraulics and the distribution of stream macroinvertebrates

    M. A. Reid


    Full Text Available Spatial variation in hydraulic conditions in streams often results in distinct water surface patterns, or surface flow types. Visual assessments of the distribution of surface flow types have been used to provide rapid assessment of habitat heterogeneity. The efficacy of this approach is predicated on the notion that surface flow types consistently represent a distinct suite of hydraulic conditions with biological relevance. This study tested this notion, asking three specific questions. First, do surface flow types provide a characterisation of physical habitat that is relevant to macroinvertebrates? Second, how well do near-bed hydraulic conditions explain macroinvertebrate distributions? Third, what components of near-bed hydraulic conditions exert the strongest influence on macroinvertebrate distributions?

    Results show that hydraulic conditions (incorporating direct measurements of near-bed velocity and turbulence in three dimensions and substratum character (incorporating estimates of particle size distribution, and biofilm and macrophyte cover within each surface flow type were largely distinct and that macroinvertebrate assemblages differed across flow types in taxon richness and assemblage composition, thus supporting the notion that rapid assessments of surface flow type distributions provide biologically relevant information.

    Macroinvertebrate assemblages were most strongly correlated with water depth, size of a flow type patch, near-bed velocity in the downstream direction, turbulence in the transverse direction, % pebble, % sand, % silt and clay and macrophyte cover. This study suggests that surface flow type mapping provides an assessment of physical habitat that is relevant to macroinvertebrates. The strong relationship detected between macroinvertebrate assemblages and transverse turbulence also highlights the value of directly measuring near-bed hydraulics. Further investigations are required to test the

  1. Flow Cytometric Assessment of Bacterial Abundance in Soils, Sediments and Sludge.

    Frossard, Aline; Hammes, Frederik; Gessner, Mark O


    Bacterial abundance is a fundamental measure in microbiology, but its assessment is often tedious, especially for soil, and sediment samples. To overcome this limitation, we adopted a time-efficient flow-cytometric (FCM) counting method involving cell detachment and separation from matrix particles by centrifugation in tubes receiving sample suspensions and Histodenz(®) solution. We used this approach to assess bacterial abundances in diverse soils (natural and agricultural), sediments (streams and lakes) and sludge from sand-filters in a drinking water treatment plant and compared the results to bacterial abundances determined by two established methods, epifluorescence microscopy (EM) and adenosine triphosphate (ATP) quantification. Cell abundances determined by FCM and EM correlated fairly well, although absolute cell abundances were generally lower when determined by FCM. FCM also showed significant relations with cell counts converted from ATP concentrations, although estimates derived from ATP determinations were typically higher, indicating the presence of ATP sources other than bacteria. Soil and sediment organic matter (OM) content influenced the goodness of fit between counts obtained with EM and FCM. In particular, bacterial abundance determined by FCM in samples containing less than 10% OM, such as stream sediment, was particularly well correlated with the cell counts assessed by EM. Overall, these results suggest that FCM following cell detachment and purification is a useful approach to increase sample throughput for determining bacterial abundances in soils, sediments and sludge. However, notable scatter and only partial concordance among the FCM and reference methods suggests that protocols require further improvement for assessments requiring high precision, especially when OM contents in samples are high.

  2. Use of soil moisture dynamics and patterns at different spatio-temporal scales for the investigation of subsurface flow processes

    T. Blume


    Full Text Available Spatial patterns as well as temporal dynamics of soil moisture have a major influence on runoff generation. The investigation of these dynamics and patterns can thus yield valuable information on hydrological processes, especially in data scarce or previously ungauged catchments. The combination of spatially scarce but temporally high resolution soil moisture profiles with episodic and thus temporally scarce moisture profiles at additional locations provides information on spatial as well as temporal patterns of soil moisture at the hillslope transect scale. This approach is better suited to difficult terrain (dense forest, steep slopes than geophysical techniques and at the same time less cost-intensive than a high resolution grid of continuously measuring sensors. Rainfall simulation experiments with dye tracers while continuously monitoring soil moisture response allows for visualization of flow processes in the unsaturated zone at these locations. Data was analyzed at different spacio-temporal scales using various graphical methods, such as space-time colour maps (for the event and plot scale and binary indicator maps (for the long-term and hillslope scale. Annual dynamics of soil moisture and decimeter-scale variability were also investigated. The proposed approach proved to be successful in the investigation of flow processes in the unsaturated zone and showed the importance of preferential flow in the Malalcahuello Catchment, a data-scarce catchment in the Andes of Southern Chile. Fast response times of stream flow indicate that preferential flow observed at the plot scale might also be of importance at the hillslope or catchment scale. Flow patterns were highly variable in space but persistent in time. The most likely explanation for preferential flow in this catchment is a combination of hydrophobicity, small scale heterogeneity in rainfall due to redistribution in the canopy and strong gradients in unsaturated conductivities leading to

  3. Numerical model of compressible gas flow in soil pollution control


    Based on the theory of fluid dynamics in porous media, a numerical model of gas flow in unsaturated zone is developed with the consideration of gas density change due to variation of air pressure. This model is characterized of its wider range of availability. The accuracy of this numerical model is analyzed through comparison with modeling results by previous model with presumption of little pressure variation and the validity of this numerical model is shown. Thus it provides basis for the designing and management of landfill gas control system or soil vapor ex.action system in soil pollution control.

  4. Changes in land cover, rainfall and stream flow in Upper Gilgel Abbay catchment, Blue Nile basin – Ethiopia

    T. H. M. Rientjes


    Full Text Available In this study we evaluated changes in land cover and rainfall in the Upper Gilgel Abbay catchment in the Upper Blue Nile basin and how changes affected stream flow in terms of annual flow, high flows and low flows. Land cover change assessment was through classification analysis of remote sensing based land cover data while assessments on rainfall and stream flow data are by statistical analysis. Results of the supervised land cover classification analysis indicated that 50.9 % and 16.7 % of the catchment area was covered by forest in 1973 and 2001, respectively. This significant decrease in forest cover is mainly due to expansion of agricultural land.

    By use of a change detection procedure, three periods were identified for which changes in rainfall and stream flow were analyzed. Rainfall was analyzed at monthly base by use of the Mann-Kendall test statistic and results indicated a statistically significant, decreasing trend for most months of the year. However, for the wet season months of June, July and August rainfall has increased. In the period 1973–2005, the annual flow of the catchment decreased by 12.1 %. Low flow and high flow at daily base were analyzed by a low flow and a high flow index that is based on a 95 % and 5 % exceedance probability. Results of the low flow index indicated decreases of 18.1 % and 66.6 % for the periods 1982–2000 and 2001–2005 respectively. Results of high flows indicated an increase of 7.6 % and 46.6 % for the same periods. In this study it is concluded that over the period 1973–2005 stream flow has changed in the Gilgel Abbay catchment by changes in land cover and changes in rainfall.


    ZHANG Jin-feng; YUAN Shou-qi; FU Yong-hong; FANG Yu-jian


    Numerical simulation of 3-D inner flow between Up-stream Pumping Mechanical Face Seals (UPMFS) faces was initially done by CFD software, which made the flow visualization come true.Simulation results directly discover the action of hydrodynamic lubrication, and by comparison with that of Conventional Mechanic Face Seals (CMFS), the advantage over bigger bearing capability, less friction and much less leakage are explained clearly.Otherwise there are also some different ideas and results from precedent analysis and computational research results: dynamic and static pressure profiles can be obtained respectively instead of the analytic total pressure distribution only, pressure distribution is nonlinear, while always be solved as linear, lower pressure is observed at the area of inner diameter caused by the grooves, but its possible cavitations effects to the performance of UPMFS still need further study.

  6. The role of glaciers in stream flow from the Nepal Himalaya

    Alford, D.; Armstrong, R.


    Shuttle Radar Topography Mission (SRTM3) data and water and energy exchange gradients. Based on these methodologies, it is estimated that the contribution of glacier annual melt water to annual stream flow into the Ganges Basin from the glacierized catchments of the Nepal Himalaya represents approximately 4% of the total annual stream flow volume of the rivers of Nepal, and thus, is a minor component of the annual flow of the Ganges River. The models developed for this study indicate that neither stream flow timing nor volume of the rivers flowing into the Ganges Basin from Nepal will be affected materially by a continued retreat of the glaciers of the Nepal Himalaya.

  7. Surface flow structure of the Gulf Stream from composite imagery and satellite-tracked drifters

    C. P. Mullen


    Full Text Available A unique set of coutemporaneous satellite-tracked drifters and five-day composite Advanced Very High Resolution Radionmeter (AVHRR satellite imagery of the North Atlantic has been analyzed to examine the surface flow structure of the Gulf Stream. The study region was divided into two sections, greater than 37° N and less than 37° N, in order to answer the question of geographic variability. Fractal and spectral analyses methods were applied to the data. Fractal analysis of the Lagrangian trajectories showed a fractal dimension of 1.21 + 0.02 with a scaling range of 83 - 343 km. The fractal dimension of the temperature fronts of the composite imagery is similar for the two regions with D = 1.11 + 0.01 over a scaling range of 4 - 44 km. Spectral analysis also reports a fairly consistent value for the spectral slope and its scaling range. Therefore, we conclude there is no geographic variability in the data set. A suitable scaling range for this contemporaneous data set is 80 - 200 km which is consistent with the expected physical conditions in the region. Finally, we address the idea of using five-day composite imagery to infer the surface flow of the Gulf Stream. Close analyses of the composite thermal fronts and the Lagrangian drifter trajectories show that the former is not a good indicator of the latter.

  8. Methods for estimating flow-duration curve and low-flow frequency statistics for ungaged locations on small streams in Minnesota

    Ziegeweid, Jeffrey R.; Lorenz, David L.; Sanocki, Chris A.; Czuba, Christiana R.


    Knowledge of the magnitude and frequency of low flows in streams, which are flows in a stream during prolonged dry weather, is fundamental for water-supply planning and design; waste-load allocation; reservoir storage design; and maintenance of water quality and quantity for irrigation, recreation, and wildlife conservation. This report presents the results of a statewide study for which regional regression equations were developed for estimating 13 flow-duration curve statistics and 10 low-flow frequency statistics at ungaged stream locations in Minnesota. The 13 flow-duration curve statistics estimated by regression equations include the 0.0001, 0.001, 0.02, 0.05, 0.1, 0.25, 0.50, 0.75, 0.9, 0.95, 0.99, 0.999, and 0.9999 exceedance-probability quantiles. The low-flow frequency statistics include annual and seasonal (spring, summer, fall, winter) 7-day mean low flows, seasonal 30-day mean low flows, and summer 122-day mean low flows for a recurrence interval of 10 years. Estimates of the 13 flow-duration curve statistics and the 10 low-flow frequency statistics are provided for 196 U.S. Geological Survey continuous-record streamgages using streamflow data collected through September 30, 2012.

  9. Scaling Law for Cross-stream Diffusion in Microchannels under Combined Electroosmotic and Pressure Driven Flow.

    Song, Hongjun; Wang, Yi; Pant, Kapil


    This paper presents an analytical study of the cross-stream diffusion of an analyte in a rectangular microchannel under combined electroosmotic flow (EOF) and pressure driven flow to investigate the heterogeneous transport behavior and spatially-dependent diffusion scaling law. An analytical model capable of accurately describing 3D steady-state convection-diffusion in microchannels with arbitrary aspect ratios is developed based on the assumption of the thin Electric Double Layer (EDL). The model is verified against high-fidelity numerical simulation in terms of flow velocity and analyte concentration profiles with excellent agreement (parametric analysis is then undertaken to interrogate the effect of the combined flow velocity field on the transport behavior in both the positive pressure gradient (PPG) and negative pressure gradient (NPG) cases. For the first time, the evolution from the spindle-shaped concentration profile in the PPG case, via the stripe-shaped profile (pure EOF), and finally to the butterfly-shaped profile in the PPG case is obtained using the analytical model along with a quantitative depiction of the spatially-dependent diffusion layer thickness and scaling law across a wide range of the parameter space.

  10. Modeling the Relations Between Flow Regime Components, Species Traits, and Spawning Success of Fishes in Warmwater Streams

    Craven, Scott W.; Peterson, James T.; Freeman, Mary C.; Kwak, Thomas J.; Irwin, Elise


    Modifications to stream hydrologic regimes can have a profound influence on the dynamics of their fish populations. Using hierarchical linear models, we examined the relations between flow regime and young-of-year fish density using fish sampling and discharge data from three different warmwater streams in Illinois, Alabama, and Georgia. We used an information theoretic approach to evaluate the relative support for models describing hypothesized influences of five flow regime components representing: short-term high and low flows; short-term flow stability; and long-term mean flows and flow stability on fish reproductive success during fish spawning and rearing periods. We also evaluated the influence of ten fish species traits on fish reproductive success. Species traits included spawning duration, reproductive strategy, egg incubation rate, swimming locomotion morphology, general habitat preference, and food habits. Model selection results indicated that young-of-year fish density was positively related to short-term high flows during the spawning period and negatively related to flow variability during the rearing period. However, the effect of the flow regime components varied substantially among species, but was related to species traits. The effect of short-term high flows on the reproductive success was lower for species that broadcast their eggs during spawning. Species with cruiser swimming locomotion morphologies (e.g., Micropterus) also were more vulnerable to variable flows during the rearing period. Our models provide insight into the conditions and timing of flows that influence the reproductive success of warmwater stream fishes and may guide decisions related to stream regulation and management.

  11. Identify temporal trend of air temperature and its impact on forest stream flow in Lower Mississippi River Alluvial Valley using wavelet analysis

    Ying Ouyang; Prem B. Parajuli; Yide Li; Theodor D. Leininger; Gary Feng


    Characterization of stream flow is essential to water resource management, water supply planning, environmental protection, and ecological restoration; while air temperature variation due to climate change can exacerbate stream flow and add instability to the flow. In this study, the wavelet analysis technique was employed to identify temporal trend of air temperature...

  12. Flow injection with in-line reduction column and conductometric detection for determination of total inorganic nitrogen in soil.

    Yanu, Pattama; Jakmunee, Jaroon


    A cost effective flow injection (FI) conductometric system has been developed for determination of total inorganic nitrogen (TIN). The system is aimed for evaluation of nitrogen nutrient in soil for agricultural application. Inorganic nitrogen compounds were extracted from soil according to the standard method by using potassium chloride solution as an extractant, and the extracted solution was then injected into the FI system. Nitrate and nitrite are converted to ammonium ion by an in-line reduction column packed with a Devarda's alloy. A gas diffusion unit was incorporated into the FI system to separate ammonium ion from other ions in a donor stream by forming ammonia gas that can diffuse through a PTFE membrane to re-dissolve in an acceptor stream. Conductance of the acceptor stream was directly proportional to ammonium ion concentration. Various parameters affecting reduction efficiency of the column, e.g., column diameter, column packing procedure, and column length was investigated and optimized. A linear calibration graph in the range of 2.00-60.00 mg L(-1) N-NH4(+) (y=0.123x+0.039, R(2) =0.997) was obtained with a limit of detection of 0.47 mg L(-1). Sample throughput of 20 samples h(-1) was achieved. The result of developed method was correlated with total Kjeldahl nitrogen (TKN) obtained from the Kjeldahl digestion method. The proposed method could be used as an alternative method to the Kjeldahl method for determination of TIN in soil.

  13. Moving Beyond Whole-stream Tracer Injections to Understand the Role of Flow and Geomorphic Variability in Stream and River Ecosystems

    Harvey, J. W.


    Flow in aquatic ecosystems affects ecological processes by influencing how sediments and nutrients are stored and transformed. Decades of tracer-addition experiments in streams have been central in revealing the key physical-biological linkages. The averaging of heterogeneous processes made possible by injecting tracers during steady baseflow conditions has allowed the individual roles of transport, storage, and biogeochemical reactions that influence stream ecological health to be clearly separated. However, fluvial systems are inherently unsteady, with flow and sediment transport continually readjusting to one another. Also, very few investigators have addressed effects of temporal variability in flow or interactions that occur between hydrologic or geomorphic processes. Thus, whole-stream tracer addition experiments often end up having limited transferability beyond the very specific flow and geomorphic conditions under which the experiments were conducted. Furthermore, there is increasing recognition that, no matter what measurement technique is used (e.g. hydraulic or tracer-based) or what model is employed, the results are almost always limited by a "window of detection" that is determined by measurement spacing and frequency, sensitivity, and by experiment duration. To counter these challenges, field investigators are increasingly supplementing whole-stream injections with additional measurements that help address different spatial and temporal scales. Furthermore they are often using multi-scale models to more fully evaluate of the full spectrum of water fluxes and biogeochemical reaction rates involved. Often the goal is to identify the combinations of flow and geomorphic conditions which enhance a particular biogeochemical reaction (e.g. dentrification, removal of toxic metals, etc.), or to rank by importance the extent of reactions occurring in different sub-environments. Examples of studies in streams, wetlands, and floodplains range in spatial scale

  14. Rain and channel flow supplements to subsurface water beneath hyper-arid ephemeral stream channels

    Kampf, Stephanie K.; Faulconer, Joshua; Shaw, Jeremy R.; Sutfin, Nicholas A.; Cooper, David J.


    In hyper-arid regions, ephemeral stream channels are important sources of subsurface recharge and water supply for riparian vegetation, but few studies have documented the subsurface water content dynamics of these systems. This study examines ephemeral channels in the hyper-arid western Sonoran Desert, USA to determine how frequently water recharges the alluvial fill and identify variables that affect the depth and persistence of recharge. Precipitation, stream stage, and subsurface water content measurements were collected over a three-year study at six channels with varying contributing areas and thicknesses of alluvial fill. All channels contain coarse alluvium composed primarily of sands and gravels, and some locations also have localized layers of fine sediment at 2-3 m depth. Rain alone contributed 300-400 mm of water input to these channels over three years, but water content responses were only detected for 36% of the rain events at 10 cm depth, indicating that much of the rain water was either quickly evaporated or taken up by plants. Pulses of water from rain events were detected only in the top meter of alluvium. The sites each experienced ⩽5 brief flow events, which caused transient saturation that usually lasted only a few hours longer than flow. These events were the only apparent source of water to depths >1 m, and water from flow events quickly percolated past the deepest measurement depths (0.5-3 m). Sustained saturation in the shallow subsurface only developed where there was a near-surface layer of finer consolidated sediments that impeded deep percolation.

  15. Cross-stream migration of a surfactant-laden deformable droplet in a Poiseuille flow

    Das, Sayan; Mandal, Shubhadeep; Chakraborty, Suman


    The motion of a viscous deformable droplet suspended in an unbounded Poiseuille flow in the presence of bulk-insoluble surfactants is studied analytically. Assuming the convective transport of fluid to be negligible, we perform a small-deformation perturbation analysis to obtain the droplet migration velocity. The droplet dynamics strongly depends on the distribution of surfactants along the droplet interface, which is governed by the relative strength of convective transport of surfactants as compared with the diffusive transport of surfactants. The present study is focused on the following two limits: (i) when the surfactant transport is dominated by surface diffusion and (ii) when the surfactant transport is dominated by surface convection. In the first limiting case, it is seen that the axial velocity of the droplet decreases with an increase in the advection of the surfactants along the surface. The variation of cross-stream migration velocity, on the other hand, is analyzed over three different regimes based on the ratio of the viscosity of the droplet phase to that of the carrier phase (λ). In the first regime (˜λ migration velocity decreases with an increase in surface advection of the surfactants, although there is no change in the direction of droplet migration. For the second regime (˜0.75 migration of the droplet changes (which means the droplet moves either towards the flow centerline or away from it) depending on different parameters. In the third regime (˜λ > 11), the migration velocity is merely affected by any change in the surfactant distribution. For the other limit of higher surface advection in comparison with surface diffusion of the surfactants, the droplet always moves towards the flow centerline and the axial velocity of the droplet is found to be independent of the surfactant distribution. However, the cross-stream velocity is found to decrease with an increase in nonuniformity in surfactant distribution.

  16. Regional Regression Equations to Estimate Flow-Duration Statistics at Ungaged Stream Sites in Connecticut

    Ahearn, Elizabeth A.


    contrast, the Rearing and Growth (July-October) bioperiod had the largest standard errors, ranging from 30.9 to 156 percent. The adjusted coefficient of determination of the equations ranged from 77.5 to 99.4 percent with medians of 98.5 and 90.6 percent to predict the 25- and 99-percent exceedances, respectively. Descriptive information on the streamgages used in the regression, measured basin and climatic characteristics, and estimated flow-duration statistics are provided in this report. Flow-duration statistics and the 32 regression equations for estimating flow-duration statistics in Connecticut are stored on the U.S. Geological Survey World Wide Web application ?StreamStats? ( The regression equations developed in this report can be used to produce unbiased estimates of select flow exceedances statewide.

  17. Estimating peak-flow frequency statistics for selected gaged and ungaged sites in naturally flowing streams and rivers in Idaho

    Wood, Molly S.; Fosness, Ryan L.; Skinner, Kenneth D.; Veilleux, Andrea G.


    The U.S. Geological Survey, in cooperation with the Idaho Transportation Department, updated regional regression equations to estimate peak-flow statistics at ungaged sites on Idaho streams using recent streamflow (flow) data and new statistical techniques. Peak-flow statistics with 80-, 67-, 50-, 43-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (1.25-, 1.50-, 2.00-, 2.33-, 5.00-, 10.0-, 25.0-, 50.0-, 100-, 200-, and 500-year recurrence intervals, respectively) were estimated for 192 streamgages in Idaho and bordering States with at least 10 years of annual peak-flow record through water year 2013. The streamgages were selected from drainage basins with little or no flow diversion or regulation. The peak-flow statistics were estimated by fitting a log-Pearson type III distribution to records of annual peak flows and applying two additional statistical methods: (1) the Expected Moments Algorithm to help describe uncertainty in annual peak flows and to better represent missing and historical record; and (2) the generalized Multiple Grubbs Beck Test to screen out potentially influential low outliers and to better fit the upper end of the peak-flow distribution. Additionally, a new regional skew was estimated for the Pacific Northwest and used to weight at-station skew at most streamgages. The streamgages were grouped into six regions (numbered 1_2, 3, 4, 5, 6_8, and 7, to maintain consistency in region numbering with a previous study), and the estimated peak-flow statistics were related to basin and climatic characteristics to develop regional regression equations using a generalized least squares procedure. Four out of 24 evaluated basin and climatic characteristics were selected for use in the final regional peak-flow regression equations.Overall, the standard error of prediction for the regional peak-flow regression equations ranged from 22 to 132 percent. Among all regions, regression model fit was best for region 4 in west

  18. Estimation of low-flow statistics at ungaged sites on streams in the Lower Hudson River Basin, New York, from data in geographic information systems

    Randall, Allan D.; Freehafer, Douglas A.


    A variety of watershed properties available in 2015 from geographic information systems were tested in regression equations to estimate two commonly used statistical indices of the low flow of streams, namely the lowest flows averaged over 7 consecutive days that have a 1 in 10 and a 1 in 2 chance of not being exceeded in any given year (7-day, 10-year and 7-day, 2-year low flows). The equations were based on streamflow measurements in 51 watersheds in the Lower Hudson River Basin of New York during the years 1958–1978, when the number of streamflow measurement sites on unregulated streams was substantially greater than in subsequent years. These low-flow indices are chiefly a function of the area of surficial sand and gravel in the watershed; more precisely, 7-day, 10-year and 7-day, 2-year low flows both increase in proportion to the area of sand and gravel deposited by glacial meltwater, whereas 7-day, 2-year low flows also increase in proportion to the area of postglacial alluvium. Both low-flow statistics are also functions of mean annual runoff (a measure of net water input to the watershed from precipitation) and area of swamps and poorly drained soils in or adjacent to surficial sand and gravel (where groundwater recharge is unlikely and riparian water loss to evapotranspiration is substantial). Small but significant refinements in estimation accuracy resulted from the inclusion of two indices of stream geometry, channel slope and length, in the regression equations. Most of the regression analysis was undertaken with the ordinary least squares method, but four equations were replicated by using weighted least squares to provide a more realistic appraisal of the precision of low-flow estimates. The most accurate estimation equations tested in this study explain nearly 84 and 87 percent of the variation in 7-day, 10-year and 7-day, 2-year low flows, respectively, with standard errors of 0.032 and 0.050 cubic feet per second per square mile. The equations

  19. Vegetation as an indicator of soil properties and water quality in the Akarçay stream (Turkey).

    Serteser, Ahmet; Kargioğlu, Mustafa; Içağa, Yilmaz; Konuk, Muhsin


    In this study, the relationship among water quality, soil properties, and plant coverage in the region of the Akarçay stream was examined. Correlation analyses were carried out between soil samples taken from each of four plant communities in the Akarçay basin and water in the Akarçay stream. The four plant communities in the study area are as follows: Limonium lilacinum (Boiss. et Bal.) Wag., Alhagi pseudalhagi (M. Bieb.) Desv. Peganum harmala L., and Hordeum marinum Huds. subsp. marinum. B, Cl, EC, K, Mg, Na, pH, and SO4 data from both soil and water samples were subjected to statistical analysis, and significant correlations were obtained (p indicated that the chemical features of the soil had a major effect on water quality. The important parameters were B, Cl, EC, K, Mg, Na, pH, and SO4 for Limonium lilacinum communities; Ca, K, and pV for Peganum harmala; and B, Cl, Mg, pH, and pV for Alhagi pseudalhagi. There were also statistically significant relationships (p indicators for soil chemistry and water quality.

  20. Impact of climate change and anthropogenic activities on stream flow and sediment discharge in the Wei River basin, China

    P. Gao


    Full Text Available Reduced stream flow and increased sediment discharge are a major concern in the Yellow River basin of China which supplies water for agriculture, industry and the growing populations located along the river. Similar concerns exist in the Wei River basin which is the largest tributary of the Yellow River basin and comprises the highly eroded Loess Plateau. Better understanding of the drivers of stream flow and sediment discharge dynamics in the Wei River basin is needed for development of effective management strategies for the region and entire Yellow River basin. In this regard we analysed long term trends for water and sediment discharge during the flood season in the Wei River basin, China. Stream flow and sediment discharge data for 1932 to 2008 from existing hydrological stations located in two sub-catchments and at two points in the Wei River were analysed. Precipitation data were analysed from corresponding meteorological stations. We identified change points or transition years for the trends by the Pettitt method and, using double mass curves, we diagnosed whether they were caused by precipitation changes, human intervention, or both. We found significant decreasing trends for stream flow and sediment discharge during the flood season in both sub-catchments and in the Wei River itself. Change-point analyses further revealed that transition years existed and that rapid decline in stream flow began in 1968 (P<0.01, and that sediment discharge began in 1981 (P<0.01 in the main river. In the two sub-catchments, the transition years were 1985 (P<0.01 and 1994 (P<0.05 for water discharge, and 1978 and 1979 for sediment discharge (P<0.05, respectively. The impact of precipitation or human activity on the reduction amount after the transition years was estimated by double mass curves of precipitation vs stream flow (sediment. For reductions in stream flow and sediment discharge, the contribution rate of human

  1. Impact of climate change and anthropogenic activities on stream flow and sediment discharge in the Wei River basin, China

    P. Gao


    Full Text Available Reduced stream flow and increased sediment discharge are a major concern in the Yellow River basin of China, which supplies water for agriculture, industry and the growing populations located along the river. Similar concerns exist in the Wei River basin, which is the largest tributary of the Yellow River basin and comprises the highly eroded Loess Plateau. Better understanding of the drivers of stream flow and sediment discharge dynamics in the Wei River basin is needed for development of effective management strategies for the region and entire Yellow River basin. In this regard we analysed long-term trends for water and sediment discharge during the flood season in the Wei River basin, China. Stream flow and sediment discharge data for 1932 to 2008 from existing hydrological stations located in two subcatchments and at two points in the Wei River were analysed. Precipitation and air temperature data were analysed from corresponding meteorological stations. We identified change-points or transition years for the trends by the Pettitt method and, using double mass curves, we diagnosed whether they were caused by precipitation changes, human intervention, or both. We found significant decreasing trends for stream flow and sediment discharge during the flood season in both subcatchments and in the Wei River itself. Change-point analyses further revealed that transition years existed and that rapid decline in stream flow began in 1968 (P P P P P < 0.05, respectively. The impact of precipitation or human activity on the reduction amount after the transition years was estimated by double mass curves of precipitation vs. stream flow (sediment. For reductions in stream flow and sediment discharge, the contribution rate of human activity was found to be 82.80 and 95.56%, respectively, and was significantly stronger than the contribution rate of precipitation. This evidence clearly suggests that, in the absence of significant decreases in precipitation

  2. Vapor Flow Resistance of Dry Soil Layer to Soil Water Evaporation in Arid Environment: An Overview

    Xixi Wang


    Full Text Available Evaporation from bare sandy soils is the core component of the hydrologic cycle in arid environments, where vertical water movement dominates. Although extensive measurement and modeling studies have been conducted and reported in existing literature, the physics of dry soil and its function in evaporation is still a challenging topic with significant remaining issues. Thus, an overview of the previous findings will be very beneficial for identifying further research needs that aim to advance our understanding of the vapor flow resistance (VFR effect on soil water evaporation as influenced by characteristics of the dry soil layer (DSL and evaporation zone (EZ. In this regard, six measurement and four modeling studies were overviewed. The results of these overviewed studies, along with the others, affirm the conceptual dynamics of DSL and EZ during drying or wetting processes (but not both within dry sandy soils. The VFR effect tends to linearly increase with DSL thickness (δ when δ < 5 cm and is likely to increase as a logarithmic function of δ when δ ≥ 5 cm. The vaporization-condensation-movement (VCM dynamics in a DSL depend on soil textures: sandy soils can form a thick (10 to 20 cm DSL while sandy clay soils may or may not have a clear DSL; regardless, a DSL can function as a transient EZ, a vapor condensation zone, and/or a vapor transport medium. Based on the overview, further studies will need to generate long-term continuous field data, develop hydraulic functions for very dry soils, and establish an approach to quantify the dynamics and VFR effects of DSLs during wetting-drying cycles as well as take into account such effects  when using conventional (e.g., Penman-Monteith evaporation models.

  3. Organic waste compounds in streams: Occurrence and aquatic toxicity in different stream compartments, flow regimes, and land uses in southeast Wisconsin, 2006–9

    Baldwin, Austin K.; Corsi, Steven R.; Richards, Kevin D.; Geis, Steven W.; Magruder, Christopher


    An assessment of organic chemicals and aquatic toxicity in streams located near Milwaukee, Wisconsin, indicated high potential for adverse impacts on aquatic organisms that could be related to organic waste compounds (OWCs). OWCs used in agriculture, industry, and households make their way into surface waters through runoff, leaking septic-conveyance systems, regulated and unregulated discharges, and combined sewage overflows, among other sources. Many of these compounds are toxic at elevated concentrations and (or) known to have endocrine-disrupting potential, and often they occur as complex mixtures. There is still much to be learned about the chronic exposure effects of these compounds on aquatic populations. During 2006–9, the U.S. Geological Survey, in cooperation with the Milwaukee Metropolitan Sewerage District (MMSD), conducted a study to determine the occurrence and potential toxicity of OWCs in different stream compartments and flow regimes for streams in the Milwaukee area. Samples were collected at 17 sites and analyzed for a suite of 69 OWCs. Three types of stream compartments were represented: water column, streambed pore water, and streambed sediment. Water-column samples were subdivided by flow regime into stormflow and base-flow samples. One or more compounds were detected in all 196 samples collected, and 64 of the 69 compounds were detected at least once. Base-flow samples had the lowest detection rates, with a median of 12 compounds detected per sample. Median detection rates for stormflow, pore-water, and sediment samples were more than double that of base-flow samples. Compounds with the highest detection rates include polycyclic aromatic hydrocarbons (PAHs), insecticides, herbicides, and dyes/pigments. Elevated occurrence and concentrations of some compounds were detected in samples from urban sites, as compared with more rural sites, especially during stormflow conditions. These include the PAHs and the domestic waste

  4. Effects of stream flow intermittency on riparian vegetation of a semiarid region river (San Pedro River, Arizona)

    Stromberg, J.C.; Bagstad, K.J.; Leenhouts, J.M.; Lite, S.J.; Makings, E.


    The San Pedro River in the southwestern United States retains a natural flood regime and has several reaches with perennial stream flow and shallow ground water. However, much of the river flows intermittently. Urbanization-linked declines in regional ground-water levels have raised concerns over the future status of the riverine ecosystem in some parts of the river, while restoration-linked decreases in agricultural ground-water pumping are expected to increase stream flows in other parts. This study describes the response of the streamside herbaceous vegetation to changes in stream flow permanence. During the early summer dry season, streamside herbaceous cover and species richness declined continuously across spatial gradients of flow permanence, and composition shifted from hydric to mesic species at sites with more intermittent flow. Hydrologic threshold values were evident for one plant functional group: Schoenoplectus acutus, Juncus torreyi, and other hydric riparian plants declined sharply in cover with loss of perennial stream flow. In contrast, cover of mesic riparian perennials (including Cynodon dactylon, an introduced species) increased at sites with intermittent flow. Patterns of hydric and mesic riparian annuals varied by season: in the early summer dry season their cover declined continuously as flow became more intermittent, while in the late summer wet season their cover increased as the flow became more intermittent. Periodic drought at the intermittent sites may increase opportunities for establishment of these annuals during the monsoonal flood season. During the late summer flood season, stream flow was present at most sites, and fewer vegetation traits were correlated with flow permanence; cover and richness were correlated with other environmental factors including site elevation and substrate nitrate level and particle size. Although perennial-flow and intermittent-flow sites support different streamside plant communities, all of the plant

  5. Receptivity to free-stream disturbance waves for hypersonic flow over a blunt cone


    A high-order shock-fitting finite difference scheme is studied and used to do direc-tion numerical simulation (DNS) of hypersonic unsteady flow over a blunt cone with fast acoustic waves in the free stream, and the receptivity problem in the blunt cone hypersonic boundary layers is studied. The results show that the acoustic waves are the strongest disturbance in the blunt cone hypersonic boundary layers. The wave modes of disturbance in the blunt cone boundary layers are first, second, and third modes which are generated and propagated downstream along the wall. The results also show that as the frequency decreases, the amplitudes of wave modes of disturbance increase, but there is a critical value. When frequency is over the critial value, the amplitudes decrease. Because of the discontinuity of curvature along the blunt cone body, the maximum amplitudes as a function of frequencies are not monotone.

  6. Flows, droughts, and aliens: factors affecting the fish assemblage in a Sierra Nevada, California, stream.

    Kiernan, Joseph D; Moyle, Peter B


    The fishes of Martis Creek, in the Sierra Nevada of California (USA), were sampled at four sites annually over 30 years, 1979-2008. This long-term data set was used to examine (1) the persistence and stability of the Martis Creek fish assemblage in the face of environmental stochasticity; (2) whether native and alien fishes responded differently to a natural hydrologic regime (e.g., timing and magnitude of high and low flows); and (3) the importance of various hydrologic and physical habitat variables in explaining the abundances of native and alien fish species through time. Our results showed that fish assemblages were persistent at all sample sites, but individual species exhibited marked interannual variability in density, biomass, and relative abundance. The density and biomass of native fishes generally declined over the period of study, whereas most alien species showed no significant long-term trends. Only alien rainbow trout increased in both density and biomass at all sites over time. Redundancy analysis identified three hydrologic variables (annual 7-day minimum discharge, maximum winter discharge, and number of distinct winter floods) and two habitat variables (percentage of pool habitat and percentage of gravel substrate) that each explained a significant portion of the annual variation in fish assemblage structure. For alien taxa, their proportional contribution to the total fish assemblage was inversely related to mean annual streamflow, one-day maximum discharge in both winter and spring, and the frequency of springtime floods. Results of this study highlight the need for continuous annual monitoring of streams with highly variable flow regimes to evaluate shifts in fish community structure. Apparent successes or failures in stream management may appear differently depending on the time series of available data.

  7. Magnitude of flood flows for selected annual exceedance probabilities for streams in Massachusetts

    Zarriello, Phillip J.


    The U.S. Geological Survey, in cooperation with the Massachusetts Department of Transportation, determined the magnitude of flood flows at selected annual exceedance prob­abilities (AEPs) at streamgages in Massachusetts and from these data developed equations for estimating flood flows at ungaged locations in the State. Flood magnitudes were deter­mined for the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent AEPs at 220 streamgages, 125 of which are in Massachusetts and 95 are in the adjacent States of Connecticut, New Hamp­shire, New York, Rhode Island, and Vermont. AEP flood flows were computed for streamgages using the expected moments algorithm weighted with a recently computed regional skew­ness coefficient for New England.Regional regression equations were developed to estimate the magnitude of floods for selected AEP flows at ungaged sites from 199 selected streamgages and for 60 potential explanatory basin characteristics. AEP flows for 21 of the 125 streamgages in Massachusetts were not used in the final regional regression analysis, primarily because of regulation or redundancy. The final regression equations used general­ized least squares methods to account for streamgage record length and correlation. Drainage area, mean basin elevation, and basin storage explained 86 to 93 percent of the variance in flood magnitude from the 50- to 0.2-percent AEPs, respec­tively. The estimates of AEP flows at streamgages can be improved by using a weighted estimate that is based on the magnitude of the flood and associated uncertainty from the at-site analysis and the regional regression equations. Weighting procedures for estimating AEP flows at an ungaged site on a gaged stream also are provided that improve estimates of flood flows at the ungaged site when hydrologic characteristics do not abruptly change.Urbanization expressed as the percentage of imperviousness provided some explanatory power in the regional regression; however, it was not statistically

  8. Field Evaluation of Preferential Flow in Agricultural Soil of the Mississippi Delta

    Perkins, K. S.; Nimmo, J. R.; Rose, C. E.; Coupe, R.


    In the Bogue Phalia basin in the Delta region of northwestern Mississippi, as in many farmed areas, intensive use of agricultural chemicals raises water quality concerns. The soils are fine textured and often exhibit surface ponding and runoff after irrigation and rainfall. There is extensive surface cracking during extended dry periods. Fields are typically land-formed to promote surface flow into irrigation ditches and streams that feed into larger river ecosystems. Deep percolation below the root zone has been considered to be minimal in this area; however, unsaturated zone processes, including the effects of a declining water table, are not well understood, and there are few measured unsaturated zone data relevant to deep percolation. In this study we assessed solute transport mechanisms within and below the root zone of a fallow soybean field by performing a 2-m ring infiltration experiment. Ponding continued for 67 hours using bromide and rhodamine tracers and subsurface instruments for measuring soil-water content, matric pressure, and solution sampling. Water percolated rapidly below the pond reaching 1 m depth in as little as 30 minutes, indicating preferential flow through the root zone, possibly related to shrink/swell features. Extensive lateral flow of water at shallow depths was apparent as the surface wetted outward to several meters from the pond in all directions with some evidence of preferentiality along slope toward the drainage ditch. Deeper lateral flow was detected at solution samplers 3 m from the pond edge at 5 m depth within a few weeks. Tracer was not detected in the unsaturated zone below 5 m however; the tracer was detected at the water table 12 m below land surface within 10 weeks of the experiment with concentrations increasing over a period of 10 months. A tracer mass balance also suggests the possibility for deep preferential transport of agricultural chemicals within the Bogue Phalia basin.

  9. Assessing Ecological Flow Needs and Risks for Springs and Baseflow Streams With Growth and Climate Change

    Springer, A. E.; Stevens, L. E.


    Ecological flow needs assessments are beginning to become an important part of regulated river management, but are more challenging for unregulated rivers. Water needs for ecosystems are greater than just consumptive use by riparian and aquatic vegetation and include the magnitude, frequency, duration and timing of flows and the depth and annual fluctuations of groundwater levels of baseflow supported streams. An ecological flow needs assessment was adapted and applied to an unregulated, baseflow dependent river in the arid to semi-arid Southwestern U.S. A separate process was developed to determine groundwater sources potentially at risk from climate, land management, or groundwater use changes in a large regional groundwater basin in the same semi-arid region. In 2007 and 2008, workshops with ecological, cultural, and physical experts from agencies, universities, tribes, and other organizations were convened. Flow-ecology response functions were developed with either conceptual or actual information for a baseflow dependent river, and scoring systems were developed to assign values to categories of risks to groundwater sources in a large groundwater basin. A reduction of baseflow to the river was predicted to lead to a decline in cottonwood and willow tree abundance, decreases in riparian forest diversity, and increases in non-native tree species, such as tamarisk. These types of forest vegetation changes would likely cause reductions or loss of some bird species. Loss of riffle habitat through declines in groundwater discharge and the associated river levels would likely lead to declines in native fish and amphibian species. A research agenda was developed to develop techniques to monitor, assess and hopefully better manage the aquifers supporting the baseflow dependent river to prevent potential threshold responses of the ecosystems. The scoring system for categories of risk was applied to four systems (aquifers, springs, standing water bodies, and streams) in

  10. Stem-root flow effect on soil-atmosphere interactions and uncertainty assessments

    Kuo, Tzu-Hsien; Chen, Jen-Ping; Xue, Yongkang


    Rainfall that reaches the soil surface can rapidly move into deeper layers in the form of bulk flow through the stem-root flow mechanism. This study developed the stem-root flow parameterization scheme and coupled this scheme with the Simplified Simple Biosphere model (SSiB) to analyze its effects on land-atmospheric interactions. The SSiB model was tested in a single-column mode using the Lien Hua Chih (LHC) measurements conducted in Taiwan and HAPEX-Mobilhy (HAPEX) measurements in France. The results show that stem-root flow generally caused a decrease in soil moisture in the top soil layer and moistened the deeper soil layers. Such soil moisture redistribution results in substantial changes in heat flux exchange between land and atmosphere. In the humid environment at LHC, the stem-root flow effect on transpiration was minimal, and the main influence on energy flux was through reduced soil evaporation that led to higher soil temperature and greater sensible heat flux. In the Mediterranean environment of HAPEX, the stem-root flow substantially affected plant transpiration and soil evaporation, as well as associated changes in canopy and soil temperatures. However, the effect on transpiration could be either positive or negative depending on the relative changes in the soil moisture of the top soil vs. deeper soil layers due to stem-root flow and soil moisture diffusion processes.

  11. Comparing molecular composition of dissolved organic matter in soil and stream water: Influence of land use and chemical characteristics.

    Seifert, Anne-Gret; Roth, Vanessa-Nina; Dittmar, Thorsten; Gleixner, Gerd; Breuer, Lutz; Houska, Tobias; Marxsen, Jürgen


    Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was used to examine the molecular composition of dissolved organic matter (DOM) from soils under different land use regimes and how the DOM composition in the catchment is reflected in adjacent streams. The study was carried out in a small area of the Schwingbach catchment, an anthropogenic-influenced landscape in central Germany. We investigated 30 different soil water samples from 4 sites and different depths (managed meadow (0-5cm, 40-50cm), deciduous forest (0-5cm), mixed-coniferous forest (0-5cm) and agricultural land (0-5cm, 40-50cm)) and 8 stream samples. 6194 molecular formulae and their magnitude-weighted parameters ((O/C)w, (H/C)w, (N/C)w, (AI-mod)w, (DBE/C)w, (DBE/O)w, (DBE-O)w, (C#)w, (MW)w) were used to describe the molecular composition of the samples. The samples can be roughly divided in three groups. Group 1 contains samples from managed meadow 40-50cm and stream water, which are characterized by high saturation compared to samples from group 2 including agricultural samples and samples from the surface meadow (0-5cm), which held more nitrogen containing and aromatic compounds. Samples from both forested sites (group 3) are characterized by higher molecular weight and O/C ratio. Environmental parameters vary between sites and among these parameters pH and nitrate significantly affect chemical composition of DOM. Results indicate that most DOM in streams is of terrestrial origin. However, 120 molecular formulae were detected only in streams and not in any of the soil samples. These compounds share molecular formulae with peptides, unsaturated aliphatics and saturated FA-CHO/FA-CHOX. Compounds only found in soil samples are much more aromatic, have more double bonds and a much lower H/C ratio but higher oxygen content, which indicates the availability of fresh plant material and less microbial processed material compared to stream samples. Copyright

  12. Integration of soil microbial processes in a reactive transport model for simulating effects of root-controlled water flow on carbon and nutrient cycling

    Espeleta, J. F.; Cardon, Z. G.; Mayer, K. U.; Rastetter, E. B.; Neumann, R. B.


    The rhizosphere is a hotbed of microbial activity in terrestrial ecosystems, and numerous models of rhizosphere dynamics have been focused in two main arenas: (1) water flow and nutrient transport around roots, and (2) carbon and nutrient exchanges between roots and microbes. However, coupling of microbial processes with physical flow (water and nutrients) in soils around plant roots is key to understanding how water, carbon and nutrient cycles interact at different scales. In order to explore how spatial distribution and timing of water flow directed by plant roots shapes rhizosphere biogeochemical function, we have developed a mechanistic model that combines a microbial food web with dynamic water flow and associated solute transport (advection, diffusion and cation exchange). We used the flexibility of a previously developed code, MIN3P (a multicomponent reactive transport model developed for variably saturated porous media) and incorporated microbial processes of carbon and nitrogen uptake, assimilation and secretion; microbial growth and death; exo-enzyme production; protozoal grazing, and soil organic matter decomposition within a soil matrix. We focused our attention at the mm-spatial scale, exploring the interaction of temporal oscillations in the magnitude and direction of water flow with soil C and N gradients. In this first modeling step, we prescribed dynamic soil water content representative of the transpiration stream (soil water loss) and hydraulic redistribution (soil water gain), as well as the flux of carbon into the soil. Although we are still in the process of building explicit root and plant behavior into the model, our preliminary results suggest that the diel pulsing of water out/into the soil can potentially change patterns of microbial C/N limitation and soil N availability. We are currently expanding our model to include the effect of plant root processes (uptake and exudation) and investigating the mechanisms explaining the interplay

  13. Variability, trends, and teleconnections of stream flows with large-scale climate signals in the Omo-Ghibe River Basin, Ethiopia.

    Degefu, Mekonnen Adnew; Bewket, Woldeamlak


    This study assesses variability, trends, and teleconnections of stream flow with large-scale climate signals (global sea surface temperatures (SSTs)) for the Omo-Ghibe River Basin of Ethiopia. Fourteen hydrological indices of variability and extremes were defined from daily stream flow data series and analyzed for two common periods, which are 1972-2006 for 5 stations and 1982-2006 for 15 stations. The Mann-Kendall's test was used to detect trends at 0.05 significance level, and simple correlation analysis was applied to evaluate associations between the selected stream flow indices and SSTs. We found weak and mixed (upward and downward) trend signals for annual and wet (Kiremt) season flows. Indices generated for high-flow (flood) magnitudes showed the same weak trend signals. However, trend tests for flood frequencies and low-flow magnitudes showed little evidences of increasing change. It was also found that El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) are the major anomalies affecting stream flow variability in the Omo-Ghibe Basin. The strongest associations are observed between ENSO/Niño3.4 and the stream flow in August and September, mean Kiremt flow (July-September), and flood frequency (peak over threshold on average three peaks per year (POT3_Fre)). The findings of this study provide a general overview on the long-term stream flow variability and predictability of stream flows for the Omo-Ghibe River Basin.

  14. DNS of heat transfer in transitional, accelerated boundary layer flow over a flat plate affected by free-stream fluctuations

    Wissink, Jan G. [School of Engineering and Design, Howell Building, Brunel University, Uxbridge UB8 3PH (United Kingdom)], E-mail:; Rodi, Wolfgang [Institute for Hydromechanics, University of Karlsruhe, Kaiserstr. 12, D-76128 Karlsruhe (Germany)


    Direct numerical simulations (DNS) of flow over and heat transfer from a flat plate affected by free-stream fluctuations were performed. A contoured upper wall was employed to generate a favourable streamwise pressure gradient along a large portion of the flat plate. The free-stream fluctuations originated from a separate LES of isotropic turbulence in a box. In the laminar portions of the accelerating boundary layer flow the formation of streaks was observed to induce an increase in heat transfer by the exchange of hot fluid near the surface of the plate and cold fluid from the free-stream. In the regions where the streamwise pressure gradient was only mildly favourable, intermittent turbulent spots were detected which relaminarised downstream as the streamwise pressure gradient became stronger. The relaminarisation of the turbulent spots was reflected by a slight decrease in the friction coefficient, which converged to its laminar value in the region where the streamwise pressure gradient was strongest.




    Full Text Available The heat transfer and hydromagnetic boundary layer flow of an electrically conducting viscous ,incompressible fluid over a continuous flat surface moving in a parallel free stream is investigated. The porous infinite surface is subjected to a slightly sinusoidal transverse suction velocity distribution. The flow becomes three dimensional due to this type of suction velocity without taking into account the induced magnetic field; the mathematical analysis is presented for the hydromagnetic laminar boundary layer flow. For the asymptotic flow condition, the components of the surface skin friction and the rate of heat transfer are obtained. During discussion it is found that with the increase of Hartmann number M, the skin friction factor F1 increase sharply for lower values of theReynolds number, but for the large value it increases steadily. But if the surface velocity is more than that of free stream velocity then the reverse trend is observed.

  16. Impacts of Rainfall Variability, Land Use and Land Cover Change on Stream Flow of the Black Volta Basin, West Africa

    Komlavi Akpoti


    Full Text Available Potential implications of rainfall variability along with Land Use and Land Cover Change (LULC on stream flow have been assessed in the Black Volta basin using the SWAT model. The spatio-temporal variability of rainfall over the Black Volta was assessed using the Mann-Kendall monotonic trend test and the Sen’s slope for the period 1976–2011. The statistics of the trend test showed that 61.4% of the rain gauges presented an increased precipitation trend whereas the rest of the stations showed a decreased trend. However, the test performed at the 95% confidence interval level showed that the detected trends in the rainfall data were not statistically significant. Land use trends between the year 2000 and 2013 show that within thirteen years, land use classes like bare land, urban areas, water bodies, agricultural lands, deciduous forests and evergreen forests have increased respectively by 67.06%, 33.22%, 7.62%, 29.66%, 60.18%, and 38.38%. Only grass land has decreased by 44.54% within this period. Changes in seasonal stream flow due to LULC were assessed by defining dry and wet seasons. The results showed that from year 2000 to year 2013, the dry season discharge has increased by 6% whereas the discharge of wet season has increased by 1%. The changes in stream flows components such us surface run-off (SURF_Q, lateral flow (LAT_Q and ground water contribution to stream flow (GW_Q and also on evapotranspiration (ET changes due to LULC was evaluated. The results showed that between the year 2000 and 2013, SURF_Q and LAT_Q have respectively increased by 27% and 19% while GW_Q has decreased by 6% while ET has increased by 4.59%. The resultant effects are that the water yield to stream flow has increased by 4%.

  17. Thresholds of flow-induced bed disturbances and their effects on stream metabolism in an agricultural river

    O'Connor, Ben L.; Harvey, Judson W.; McPhillips, Lauren E.


    Storm-driven flow pulses in rivers destroy and restructure sediment habitats that affect stream metabolism. This study examined thresholds of bed disturbances that affected patch- and reach-scale sediment conditions and metabolism rates. A 4 year record of discharge and diel changes in dissolved oxygen concentrations (ΔDO) was analyzed for disturbances and recovery periods of the ΔDO signal. Disturbances to the ΔDO signal were associated with flow pulses, and the recovery times for the ΔDO signal were found to be in two categories: less than 5 days (30% of the disturbances) or greater than 15 days (70% of the disturbances). A field study was performed during the fall of 2007, which included a storm event that increased discharge from 3.1 to 6.9 m3/s over a 7 h period. During stable flow conditions before the storm, variability in patch-scale stream metabolism values were associated with sediment texture classes with values ranging from −16.4 to 2.3 g O22/d (negative sign indicates net respiration) that bounded the reach-averaged rate of −5.6 g O22/d. Hydraulic modeling of bed shear stresses demonstrated a storm-induced flow pulse mobilized approximately 25% of the bed and reach-scale metabolism rates shifted from −5 to −40 g O22/d. These results suggest that storm-induced bed disturbances led to threshold behavior with respect to stream metabolism. Small flow pulses resulted in partial-bed mobilization that disrupted stream metabolism by increased turbidity with short recovery times. Large flow pulses resulted in full-bed mobilization that disrupted stream metabolism by destroying periphyton habitats with long recovery times.

  18. Dealing with emerging waste streams: used tyre assessment in Thailand using material flow analysis.

    Jacob, Paul; Kashyap, Prakriti; Suparat, Tasawan; Visvanathan, Chettiyappan


    Increasing urbanisation and automobile use have given rise to an increase in global tyre waste generation. A tyre becomes waste once it wears out and is no longer fit for its original purpose, and is thus in its end-of-life state. Unlike in developed countries, where waste tyre management has already become a significant issue, it is rarely a priority waste stream in developing countries. Hence, a large quantity of waste tyres ends up either in the open environment or in landfill. In Thailand, waste tyre management is in its infancy, with increased tyre production and wider use of vehicles, but low levels of recycling, leaving scope for more appropriate policies, plans and strategies to increase waste tyre recycling. This article describes the journey of waste tyres in Thailand in terms of recycling and recovery, and disposal. Material flow analysis was used as a tool to quantify the flows and accumulation of waste tyres in Thailand in 2012. The study revealed that, in Thailand in 2012, waste tyre management was still biased towards destructive technologies (48.9%), rather than material recovery involving rubber reclamation, retreading tyres and whole and shredded tyre applications (6.7%). Despite having both economic and environmental benefits, 44.4% of used tyres in 2012 were dumped in the open environment, and the remaining 0.05% in landfills. © The Author(s) 2014.

  19. Methods for estimating selected low-flow frequency statistics and mean annual flow for ungaged locations on streams in North Georgia

    Gotvald, Anthony J.


    The U.S. Geological Survey, in cooperation with the Georgia Department of Natural Resources, Environmental Protection Division, developed regional regression equations for estimating selected low-flow frequency and mean annual flow statistics for ungaged streams in north Georgia that are not substantially affected by regulation, diversions, or urbanization. Selected low-flow frequency statistics and basin characteristics for 56 streamgage locations within north Georgia and 75 miles beyond the State’s borders in Alabama, Tennessee, North Carolina, and South Carolina were combined to form the final dataset used in the regional regression analysis. Because some of the streamgages in the study recorded zero flow, the final regression equations were developed using weighted left-censored regression analysis to analyze the flow data in an unbiased manner, with weights based on the number of years of record. The set of equations includes the annual minimum 1- and 7-day average streamflow with the 10-year recurrence interval (referred to as 1Q10 and 7Q10), monthly 7Q10, and mean annual flow. The final regional regression equations are functions of drainage area, mean annual precipitation, and relief ratio for the selected low-flow frequency statistics and drainage area and mean annual precipitation for mean annual flow. The average standard error of estimate was 13.7 percent for the mean annual flow regression equation and ranged from 26.1 to 91.6 percent for the selected low-flow frequency equations.The equations, which are based on data from streams with little to no flow alterations, can be used to provide estimates of the natural flows for selected ungaged stream locations in the area of Georgia north of the Fall Line. The regression equations are not to be used to estimate flows for streams that have been altered by the effects of major dams, surface-water withdrawals, groundwater withdrawals (pumping wells), diversions, or wastewater discharges. The regression

  20. Simulation of soil water regimes including pedotransfer functions and land-use related preferential flow

    Sonneveld, M.P.W.; Backx, M.A.H.M.; Bouma, J.


    Differences in land use history among taxonomically identical soils often result in different hydraulic properties, derived from either laboratory measurements or pedotransfer functions (PTFs). Additionally, flow mechanisms in sandy soils may also change through differences in water repellency

  1. Soil pipe flow tracer experiments: 2. Application of a transient storage zone model

    Soil pipes, defined here as discrete preferential flow paths generally parallel to the slope, are important subsurface flow pathways that play a role in many soil erosion phenomena. However, limited research has been performed on quantifying and characterizing their flow and transport characteristic...

  2. Comparison among monitoring strategies to assess water flow dynamic and soil hydraulic properties in agricultural soils

    Javier Valdes-Abellan


    Full Text Available Abstract Irrigated agriculture is usually performed in semi-arid regions despite scarcity of water resources. Therefore, optimal irrigation management by monitoring the soil is essential, and assessing soil hydraulic properties and water flow dynamics is presented as a first measure. For this purpose, the control of volumetric water content, θ, and pressure head, h, is required. This study adopted two types of monitoring strategies in the same experimental plot to control θ and h in the vadose zone: i non-automatic and more time-consuming; ii automatic connected to a datalogger. Water flux was modelled with Hydrus-1D using the data collected from both acquisition strategies independently (3820 daily values for the automatic; less than 1000 for the non-automatic. Goodness-of-fit results reported a better adjustment in case of automatic sensors. Both model outputs adequately predicted the general trend of θ and h, but with slight differences in computed annual drainage (711 mm and 774 mm. Soil hydraulic properties were inversely estimated from both data acquisition systems. Major differences were obtained in the saturated volumetric water content, θs, and the n and α van Genuchten model shape parameters. Saturated hydraulic conductivity, Ks, shown lower variability with a coefficient of variation range from 0.13 to 0.24 for the soil layers defined. Soil hydraulic properties were better assessed through automatic data acquisition as data variability was lower and accuracy was higher.

  3. Comparison among monitoring strategies to assess water flow dynamic and soil hydraulic properties in agricultural soils

    Valdes-Abellan, J.; Jiménez-Martínez, J.; Candela, L.; Tamoh, K.


    Irrigated agriculture is usually performed in semi-arid regions despite scarcity of water resources. Therefore, optimal irrigation management by monitoring the soil is essential, and assessing soil hydraulic properties and water flow dynamics is presented as a first measure. For this purpose, the control of volumetric water content, θ, and pressure head, h, is required. This study adopted two types of monitoring strategies in the same experimental plot to control θ and h in the vadose zone: i) non-automatic and more time-consuming; ii) automatic connected to a datalogger. Water flux was modelled with Hydrus-1D using the data collected from both acquisition strategies independently (3820 daily values for the automatic; less than 1000 for the non-automatic). Goodness-of-fit results reported a better adjustment in case of automatic sensors. Both model outputs adequately predicted the general trend of θ and h, but with slight differences in computed annual drainage (711 mm and 774 mm). Soil hydraulic properties were inversely estimated from both data acquisition systems. Major differences were obtained in the saturated volumetric water content, θs, and the n and α van Genuchten model shape parameters. Saturated hydraulic conductivity, Ks, shown lower variability with a coefficient of variation range from 0.13 to 0.24 for the soil layers defined. Soil hydraulic properties were better assessed through automatic data acquisition as data variability was lower and accuracy was higher. (Author)

  4. Groundwater Management Policies for Maintaining Stream Flow Given Variable Climatic Conditions

    Pohll, G.; Carroll, R. W.; Brozovic, N.


    Groundwater is an important resource to agriculture throughout the semi-arid United States, where farmers often supplement surface water diversions with groundwater pumping. Understanding the complex exchange over space and time between rivers and aquifers is important in developing management alternatives that are capable of preserving stream flow for habitat and increasing water deliveries downstream while minimizing lost crop production. Previous integrated hydrologic-economic models have generally assumed superposition of the impacts of groundwater pumping on the hydrologic system for analytical tractability. Although this assumption may be reasonable for some surface water-groundwater systems, in many systems the behavior diverges considerably from the linear assumption. We present analyses using an integrated hydrologic-economic model of surface water-groundwater interaction with nonlinear dynamics, developed for the Mason Valley area in Nevada. The study area has active water conflict between upstream and downstream water users, where groundwater pumping has an important impact on streamflow. The model replicates the movement of water throughout the coupled river and aquifer of the Walker River system and is used to analyze hypothetical tradeoffs between increasing streamflow at the basin outlet and meeting crop water demands for irrigation. The model is run from 1997 to 2006 to capture wet and dry climatic conditions, including a four year drought period in which groundwater pumping accounts for more than 50% of the irrigated water budget. Three alternate groundwater management policies are analyzed to compare economic performance (resulting from reductions in crop area due to reduced groundwater pumping) and hydrologic impact (in terms of increased stream discharge at the basin outlet). First, uniform pumping quotas are the simplest policy to implement and are modeled here as equal reductions in groundwater pumping for each stakeholder at a lumped field

  5. Potential risk assessment in stream sediments, soils and waters after remediation in an abandoned W>Sn mine (NE Portugal).

    Antunes, I M H R; Gomes, M E P; Neiva, A M R; Carvalho, P C S; Santos, A C T


    The mining complex of Murçós belongs to the Terras de Cavaleiros Geopark, located in Trás-os-Montes region, northeast Portugal. A stockwork of NW-SE-trending W>Sn quartz veins intruded Silurian metamorphic rocks and a Variscan biotite granite. The mineralized veins contain mainly quartz, cassiterite, wolframite, scheelite, arsenopyrite, pyrite, sphalerite, chalcopyrite, galena, rare pyrrhotite, stannite, native bismuth and also later bismuthinite, matildite, joseite, roosveltite, anglesite, scorodite, zavaritskite and covellite. The exploitation produced 335t of a concentrate with 70% of W and 150t of another concentrate with 70% of Sn between 1948 and 1976. The exploitation took place mainly in four open pit mines as well as underground. Three lakes were left in the area. Remediation processes of confination and control of tailings and rejected materials and phytoremediation with macrophytes from three lakes were carried out between 2005 and 2007. Stream sediments, soils and water samples were collected in 2008 and 2009, after the remediation process. Most stream sediments showed deficiency or minimum enrichment for metals. The sequential enrichment factor in stream sediments W>Bi>As>U>Cd>Sn=Ag>Cu>Sb>Pb>Be>Zn is mainly associated with the W>Sn mineralizations. Stream sediments receiving drainage of a mine dump were found to be significantly to extremely enriched with W, while stream sediments and soils were found to be contaminated with As. Two soil samples collected around mine dumps and an open pit lake were also found to be contaminated with U. The waters from the Murçós W>Sn mine area were acidic to neutral. After the remediation, the surface waters were contaminated with F(-), Al, As, Mn and Ni and must not be used for human consumption, while open pit lake waters must also not be used for agriculture because of contamination with F(-), Al, Mn and Ni. In most waters, the As occurred as As (III), which is toxic and is easily mobilized in the drainage

  6. Influence of Large Woody Debris on Three-dimensional Flow Structure Through Meander Bends in a Low-energy Stream

    Newell, M. D.; Rhoads, B. L.


    Most theoretical research on the dynamics of meandering streams has emphasized the importance of internal mechanisms. Although there is an abundance of empirical work on external factors, theoretical development in this area has been limited, especially for biotic factors, such as LWD, which geomorphologists have long recognized constitute important external mechanisms in fluvial systems. In particular, little is known about the role of LWD in low-energy, human-modified streams. One important potential morphological influence of LWD that has not been investigated is the potential for LWD to alter flow structures through meander bends, a critical element of current meander evolution theories since three dimensional characteristics of flow through meander bends have been shown to have a significant impact on the processes of sediment transport and bank erosion, and consequently meander development. The overall goal of this project is to advance the understanding of the interactions between large woody debris and the geomorphic structure and function of low-gradient meandering streams. This improved understanding will provide a more reliable framework of knowledge on which to base stream naturalization (i.e. the return to pre-disturbance conditions) and management plans for low-energy meandering streams with abundant LWD.

  7. Persistent effects of wildfire and debris flows on the invertebrate prey base of rainbow trout in Idaho streams

    Rosenberger, A.E.; Dunham, J.B.; Buffington, J.M.; Wipfli, M.S.


    Wildfire and debris flows are important physical and ecological drivers in headwater streams of western North America. Past research has primarily examined short-term effects of these disturbances; less is known about longer-term impacts. We investigated wildfire effects on the invertebrate prey base for drift-feeding rainbow trout (Oncorhynchus mykiss, Walbaum) in Idaho headwater streams a decade after wildfire. Three stream types with different disturbance histories were examined: 1) unburned, 2) burned, and 3) burned followed by debris flows that reset channel morphology and riparian vegetation. The quantity of macroinvertebrate drift (biomass density) was more variable within than among disturbance categories. Average body weight and taxonomic richness of drift were significantly related to water temperature and influenced by disturbance history. During the autumn sampling period, the amount of terrestrial insects in rainbow trout diets varied with disturbance history and the amount of overhead canopy along the stream banks. Results indicate that there are detectable changes to macroinvertebrate drift and trout diet a decade after wildfire, and that these responses are better correlated with specific characteristics of the stream (water temperature, canopy cover) than with broad disturbance classes.

  8. Prolonged effect of fluid flow stress on the proliferative activity of mesothelial cells after abrupt discontinuation of fluid streaming

    Aoki, Shigehisa, E-mail: [Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga (Japan); Ikeda, Satoshi [Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga (Japan); Takezawa, Toshiaki [Transgenic Animal Research Center, National Institute of Agrobiological Sciences, Ibaraki (Japan); Kishi, Tomoya [Department of Internal Medicine, Saga University, Saga (Japan); Makino, Junichi [Makino Clinic, Saga (Japan); Uchihashi, Kazuyoshi; Matsunobu, Aki [Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga (Japan); Noguchi, Mitsuru [Department of Urology, Faculty of Medicine, Saga University, Saga (Japan); Sugihara, Hajime [Department of Physical Therapy, International University of Health and Welfare, Fukuoka (Japan); Toda, Shuji [Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga (Japan)


    Highlights: Black-Right-Pointing-Pointer Late-onset peritoneal fibrosis leading to EPS remains to be elucidated. Black-Right-Pointing-Pointer Fluid streaming is a potent factor for peritoneal fibrosis in PD. Black-Right-Pointing-Pointer We focused on the prolonged effect of fluid streaming on mesothelial cell kinetics. Black-Right-Pointing-Pointer A history of fluid streaming exposure promoted mesothelial proliferative activity. Black-Right-Pointing-Pointer We have thus identified a potent new factor for late-onset peritoneal fibrosis. -- Abstract: Encapsulating peritoneal sclerosis (EPS) often develops after transfer to hemodialysis and transplantation. Both termination of peritoneal dialysis (PD) and transplantation-related factors are risks implicated in post-PD development of EPS, but the precise mechanism of this late-onset peritoneal fibrosis remains to be elucidated. We previously demonstrated that fluid flow stress induced mesothelial proliferation and epithelial-mesenchymal transition via mitogen-activated protein kinase (MAPK) signaling. Therefore, we speculated that the prolonged bioactive effect of fluid flow stress may affect mesothelial cell kinetics after cessation of fluid streaming. To investigate how long mesothelial cells stay under the bioactive effect brought on by fluid flow stress after removal of the stress, we initially cultured mesothelial cells under fluid flow stress and then cultured the cells under static conditions. Mesothelial cells exposed to fluid flow stress for a certain time showed significantly high proliferative activity compared with static conditions after stoppage of fluid streaming. The expression levels of protein phosphatase 2A, which dephosphorylates MAPK, in mesothelial cells changed with time and showed a biphasic pattern that was dependent on the duration of exposure to fluid flow stress. There were no differences in the fluid flow stress-related bioactive effects on mesothelial cells once a certain time had passed

  9. 喇嘛溪沟泥石流形成条件及易发性评价%Formation Conditions and Proneness Evaluation of Debris Flow at Lama Stream



    雅安—泸沽高速公路途径汉源县境内文武坡喇嘛溪沟的昔格达地层,工程地质性质极差.该流域坡面受水长期冲刷,形成多条冲沟;沟道纵比降大,且侧壁松散固体物质丰富,侵蚀严重,在暴雨的诱发下有可能发生泥石流,直接对高速公路的修建与运营造成影响.在调查研究的基础上,分析了喇嘛溪沟泥石流形成的条件,对流速、冲击力、总量等进行了计算,并评价了该泥石流的易发性,结果表明:喇嘛溪沟泥石流的类型属于暴雨型稀性泥石流,相应设计概率下的暴发规模属小型,泥石流流量很小,基本以水土流失形式存在.建议采取一定的防治措施.%Ya'an-Lugu Highway passes the Xigeda Strata at Lama Stream,Wenwu Slope,Hanyuan County,subject to adverse engineering geological properties.There are many gullies formed due to long-term water erosion on slope surface in this river basin.As a result of large vertical slope,loose sidewall,rich solid matters and serious erosion,debris flow is possible to arise when induced by rainstorm,affecting the highway construction and operation directly.Based on the surveys,the formation conditions of debris flow at Lama Stream were analyzed,the flow rate,impact force and total amount calculated,and the proneness of the debris flow evaluated.The results show that the debris flow at Lama Stream is stormy and watery so that under corresponding design probability,the outbreak scale is small with small flow rate and in the form of water and soil loss basically.Thus it is recommended to adopt some prevention and control measures.

  10. Modeling the distributed effects of forest thinning on the long-term water balance and stream flow extremes for a semi-arid basin in the southwestern US

    H. A. Moreno


    Full Text Available To achieve water resources sustainability in the water-limited Southwestern US, it is critical to understand the potential effects of proposed forest thinning on the hydrology of semi-arid basins, where disturbances to headwater catchments can cause significant changes in the local water balance components and basin-wise stream flows. In Arizona, the Four Forest Restoration Initiative (4FRI is being developed with the goal of restoring 2.4 million acres of ponderosa pine along the Mogollon Rim. Using the physically based, spatially distributed tRIBS model, we examine the potential impacts of the 4FRI on the hydrology of Tonto Creek, a basin in the Verde–Tonto–Salt (VTS system, which provides much of the water supply for the Phoenix Metropolitan Area. Long-term (20 year simulations indicate that forest removal can trigger significant shifts in the spatio-temporal patterns of various hydrological components, causing increases in net radiation, surface temperature, wind speed, soil evaporation, groundwater recharge, and runoff, at the expense of reductions in interception and shading, transpiration, vadose zone moisture and snow water equivalent, with south facing slopes being more susceptible to enhanced atmospheric losses. The net effect will likely be increases in mean and maximum stream flow, particularly during El Niño events and the winter months, and chiefly for those scenarios in which soil hydraulic conductivity has been significantly reduced due to thinning operations. In this particular climate, forest thinning can lead to net loss of surface water storage by vegetation and snow pack, increasing the vulnerability of ecosystems and populations to larger and more frequent hydrologic extreme conditions on these semi-arid systems.

  11. Geomorphic, flood, and groundwater-flow characteristics of Bayfield Peninsula streams, Wisconsin, and implications for brook-trout habitat

    Fitzpatrick, Faith A.; Peppler, Marie C.; Saad, David A.; Pratt, Dennis M.; Lenz, Bernard N.


    In 2002–03, the U.S. Geological Survey conducted a study of the geomorphic, flood, and groundwater-flow characteristics of five Bayfield Peninsula streams, Wisconsin (Cranberry River, Bark River, Raspberry River, Sioux River, and Whittlesey Creek) to determine the physical limitations for brook-trout habitat. The goals of the study were threefold: (1) to describe geomorphic characteristics and processes, (2) to determine how land-cover characteristics affect flood peaks, and (3) to determine how regional groundwater flow patterns affect base flow.

  12. Phosphorus Speciation and Sorption Processes in Preferential flow paths and Soil Matrix in Forested Podzolic Till Soil

    Saastamoinen, S.; Laine-Kaulio, H.; Klöve, B.


    The importance of preferential flow paths in nutrient leaching and subsurface transport has been identified in several studies mainly on agricultural soils. In forest soils research, decayed root channels, stone surfaces and other secondary soil structures have shown to affect unsaturated flow in glacial till soil. Until recently, the focus has been on nitrogen and carbon dynamics in the preferential flow paths. Preferential flow may also have a fundamental role in phosphorus (P) sorption processes and transport from forested till soils to surface waters. The main objectives of this study were to determine how preferential flow paths affect to P speciation, sorption and leaching in forested podzolic till soil. Field experiments were conducted in mixed coniferous forest, with soil type of glacial sandy till classified as Haplic Podzol. The first experiment was conducted in Ranua, Northern Finland. The preferential flow paths were identified by introducing Acid Blue 9 dye tracer to a 1 m2 study plot. The soil profile was vertically sliced and samples were collected from the stained preferential flow paths and unstained soil matrix. Ammonium-oxalate extracted trace elements and P, total and inorganic P, inorganic P fractions and organic P forms (31P-NMR spectroscopy) were analyzed from the samples. In the second experiment in Sotkamo, Eastern Finland, three 1 m2 study plots were selected from a forested hillslope: top, middle and bottom slope. The detection of preferential flow paths and the sampling procedure was identical to the first plot experiment. Samples were analyzed for ammonium-oxalate extracted trace elements and P. Also, the effect of reaction time, P concentration and temperature on the sorption process in preferential flow paths and soil matrix was studied by kinetic batch-type sorption experiments. Stone surfaces were the most dominant preferential flow paths and contained lower oxalate-extracted and total P concentrations than the soil matrix in all

  13. Impacts from PCB accumulation on amphibians inhabiting streams flowing from the Paducah Gaseous Diffusion Plant.

    DeGarady, C J; Halbrook, R S


    Contamination at the Paducah Gaseous Diffusion Plant (PGDP), Paducah, Kentucky, has been under evaluation for many years. We studied amphibians in selected outfalls (drainage ditches) flowing from the PGDP to determine if PCBs were accumulating in their tissues and how this might affect local populations. We determined relative amphibian species richness and abundance among seven outfalls and three reference streams by listening to their calls during audio surveys. We also captured amphibians from each study site during the summers of 2000 and 2001 and analyzed their carcasses for PCBs (Aroclor 1260 and 34 congeners) and livers for ethoxyresorufin O-deethylase (EROD) activity, a biomarker of PCBs and other organic contamination. Ten species were heard across study sites, and abundance and richness at outfalls were similar to those observed at reference sites. However, there were significant differences in abundance (p = 0.001) and richness (p = 0.048) of amphibians between continuously flowing and intermittent outfalls. There were no significant differences in PCB concentrations (p = 0.113) in amphibians captured from study sites, although Aroclor 1260 concentrations tended to be higher in amphibians collected from one outfall (outfall 12) on the east side of the plant (x = 1260 microg/kg) compared with all other study sites (x = 489 microg/kg). EROD activity measured in the liver was not indicative of Aroclor 1260 concentrations in amphibians at the PGDP, and EROD did not differ by study site, species, age class, or gender. PCB concentrations measured in amphibians at the PGDP were similar to concentrations measured at reference sites and did not appear to negatively affect individual amphibians or abundance and richness.

  14. Numerical Simulation of Bubble Formation and Transport in Cross-Flowing Streams

    Yanneck Wielhorski


    Full Text Available Numerical simulations on confined bubble trains formed by cross-flowing streams are carried out with the numerical code THETIS which is based on the Volume of Fluid (VOF method and has been developed for two phase flow studies and especially for a gas-liquid system. The surface tension force, which needs particular attention in order to determine the shape of the interface accurately, is computed using the Continuum Surface Force model (CSF. Through the coupling of a VOF-PLIC technique (Piecewise-Linear Interface Calculation and a smoothing function of adjustable thickness, the Smooth Volume of Fluid technique (SVOF is intended to capture accurately strong interface distortion, rupture or reconnection with large density and viscosity contrasts between phases. This approach is extended by using the regular VOF-PLIC technique, while applying a smoothing procedure affecting both physical characteristics averaging and surface tension modeling. The front-capturing strategy is extended to gas injection. We begin by introducing the main physical phenomena occurring during bubble formation in microfluidic systems. Then, an experimental study performed in a cylindrical T-junction for different wetting behaviors is presented. For the wetting configuration, Cartesian 2D numerical simulations concerning the gas-liquid bubble production performed in a T-junction with rectangular, planar cross sections are shown and compared with experimental measurements. Finally, the results obtained of bubble break-up mechanism, shape, transport and pressure drop along the channel will be presented, discussed and compared to some experimental and numerical outcomes given in the literature.

  15. Fine Magnetic Structure and Origin of Counter-Streaming Mass Flows in a Quiescent Solar Prominence

    Shen, Yuandeng; Liu, Ying D; Chen, P F; Su, Jiangtao; Xu, Zhi; Liu, Zhong


    We present high-resolution observations of a quiescent solar prominence which was consisted of a vertical and a horizontal foot encircled by an overlying spine, and counter-streaming mass flows were ubiquitous in the prominence. While the horizontal foot and the spine were connecting to the solar surface, the vertical foot was suspended above the solar surface and supported by a semicircular bubble structure. The bubble first collapsed and then reformed at a similar height, finally, it started to oscillate for a long time. We find that the collapsing and oscillation of the bubble boundary were tightly associated with a flare-like feature located at the bottom of the bubble. Based on the observational results, we propose that the prominence should be composed of an overlying horizontal spine encircling a low-lying horizontal and a vertical foot, in which the horizontal foot was consisted of shorter field lines running partially along the spine and with the both ends connecting to the solar surface, while the v...

  16. Determining the potential contribution of hyporheic flow to nitrogen and phosphorus retention in streams in a northern California watershed

    Orr, C. H.; Schade, J. D.; Thomas, S. A.


    An ongoing effort at the Angelo Coast Range Reserve in the Eel River watershed in Northern California has aimed to understand how stream network position influences feedbacks between nutrient cycles, stream metabolism, and consumer-resource interactions. This includes identifying when biotic interactions and organism metabolism are important determinants of nutrient flux and the ratio of nutrients retained. In general, ecosystem nutrient retention is hard to measure because difficulties arise in determining ecosystem boundaries. In streams we tend to measure the retention of limiting nutrients on a reach scale, assuming that nutrients retained are taken up by benthic organisms available to be influenced by higher-order trophic interactions, while at the same time acknowledging some fraction of stream water is interacting with the subsurface of the stream and nutrients are being retained there. Plateau nutrient addition experiments of N + P together were conducted in six streams with watershed areas between 0.6 - 145 km2. We used independent lab measurements of hyporheic sediment metabolism and retention of soluble nitrogen and phosphorus, with the reach-scale nutrient uptake and transient storage measurements to determine 1) the potential for hyporheic uptake to be contributing to the overall measured N and P uptake rates, 2) the hyporheic-surface exchange required to produce these rates and 3) the reasonableness of this exchange given transient storage values for the reach. Subsurface biotic and abiotic uptake was also measured. Subsurface uptake rates ranged from 0.5 - 5.9 µg NH4* kg-1 wet sediment and 20-50 µg PO4-P * kg-1 wet sediment and there is evidence that 66-100% of P uptake could be abiotic. In the smallest stream, nitrogen retention rates of ~5.0 µg NH4 m-2*s-1 were measured in entirely subsurface flow, compared with reach-scale retention of ~0.18 µg NH4 m-2*s-1 for the same stream. Hyporheic uptake could account for all of the surface water loss

  17. Introducing Fractal Dimension to Estimation of Soil Sensitivity to Preferential Flow


    Food dye Brilliant Blue was introduced as the tracer in a dye-tracing experiment to obtain dye profile patterns of sandy loam soil, aeolian sandy soil, percolating paddy soil and permeable paddy soil. The dyed soil profiles were then photographed and the photos were scanned into a computer. Edited with certain software, only the dyed areas were left on the profile photos, which indicted the preferential flow paths for water and solute transport. Fractal dimensions of the dye patterns were calculated according to Arnold's function. Soil particle size distribution was analyzed by pipette method. The regression analysis showed that there was significant relationship between soil clay content and fractal dimension D of the dye pattern of soil profile. Based on the experiment results, the possibility of introducing fractal dimension to estimation of soil sensitivity to preferential flow is discussed.

  18. A Numerical Treatment of Nondimensional Form of Water Quality Model in a Nonuniform Flow Stream Using Saulyev Scheme

    Nopparat Pochai


    Full Text Available The stream water quality model of water quality assessment problems often involves numerical methods to solve the equations. The governing equation of the uniform flow model is one-dimensional advection-dispersion-reaction equations (ADREs. In this paper, a better finite difference scheme for solving ADRE is focused, and the effect of nonuniform water flows in a stream is considered. Two mathematical models are used to simulate pollution due to sewage effluent. The first is a hydrodynamic model that provides the velocity field and elevation of the water flow. The second is a advection-dispersion-reaction model that gives the pollutant concentration fields after input of the velocity data from the hydrodynamic model. For numerical techniques, we used the Crank-Nicolson method for system of a hydrodynamic model and the explicit schemes to the dispersion model. The revised explicit schemes are modified from two computation techniques of uniform flow stream problems: forward time central space (FTCS and Saulyev schemes for dispersion model. A comparison of both schemes regarding stability aspect is provided so as to illustrate their applicability to the real-world problem.

  19. Characteristics of Channeling Flow in Cultivated Horizon of Saline Rice Soil

    LUO Jinming; DENG Wei; ZHANG Xiaoping; YANG Fan; LI Xiujun


    By applying bromide ion as tracer, the channeling flow has been quantitatively described in saline rice soil and alkaline soil of Da'an City, Jilin Province of China. Breakthrough curves of bromide ion in the saline rice soils after 1-year cultivation and 5-year cultivation and alkaline soil have been attained. Results show that the rice cultivation practice can improve the alkaline soil structure, however, it can accelerate the development of channeling flow pathway.Therefore, the channeling flow pathway has been developed widely in saline rice soil, but rarely in the alkaline soil.Three models of convection-dispersion equation (CDE), transfer functional model (TFM) and Back-Progation Network (BP Network) were used to simulate the transportation process of bromide ion. The peaks of probability density function of saline rice soil are higher with left skewed feature compared with that of the alkaline soil. It shows that the TFM and CDE can simulate the transportation process of the bromide ion in saline rice soil after 5-year cultivation, however, some deviation exists when it was used to simulate transportation process of bromide ion in saline rice soil after 1-year cultivation and alkaline soil; BP network can effectively simulate transportation process of bromide ion in both saline rice soil and alkaline soil.

  20. Response of Tropical Stream Fish Assemblages to Small Hydropower Induced Flow Alteration in the Western Ghats of Karnataka, India.

    Rao, S. T.


    Alteration of natural flow regime is considered as one of the major threats to tropical stream fish assemblages as it alters the physio-chemical and micro-habitat features of the river. Flow alteration induced by Small hydro-power (SHP) plants disrupts the flow regime by flow diversion and regulation. The effects of flow alteration on tropical stream fish assemblages, especially in the Western Ghats of India is largely understudied. Such a knowledge is imperative to set limits on flow alteration as SHPs in the Western Ghats are being planned at an unprecedented rate with exemption from environment impact assessments and backing in the form of government subsidies and carbon credits. This study aimed to understand the response of fish assemblages to SHP induced flow alteration in a regulated and unregulated tributary of the Yettinahole River in the Western Ghats of Karnataka. The study intended to quantify the natural and altered flow regime using automated periodic depth measurements, its effect on micro-habitats and environmental variables and finally, understand how fish assemblages respond to such changes. The response of fish assemblage was measured in terms of catch-per-site, species-regime associations and ecological distance between the regimes. The study used a space for time substitution approach and found that the altered flow regime dampened the diurnal and seasonal patterns of natural flow regime. The altered flow regime influenced variations in water quality, micro-habitat heterogeneity and fish assemblage response, each characteristic of the type of flow alteration. The natural flow regime was found to have a higher catch-per-site and strong associations with endemic and niche-specific taxa. Compositional dissimilarities, in terms of ecological distance were observed between the altered and the natural flow regime. Dewatered or flow diverted regime contained species with lentic affinities while an overall low catch-per-site and weak species

  1. Sulfur flow in a soil-plant system-effects of long-term treatment history and soil properties

    Boye, Kristin; Eriksen, Jørgen; Nilsson, Ingvar;


    organic S) in the soil were involved in the S transformations. The long-term FYM treatment had resulted in higher S cycling rates and a slightly higher resistance to S deficiency than the CR treatment. The influence of soil type on S flow patterns was important, but probably only partly related...

  2. Meso-scale resolution for the definition of environmental flow standards in Mediterranean streams

    Vezza, Paolo; Martinez-Capel, Francisco; Muñoz-Mas, Rafael; Comoglio, Claudio; Spairani, Michele; Koutrakis, Emmanuil; Sapounidis, Argyris


    high sensitivity/specificity values, indicating substantial predictions with low cross-classification errors. In addition, the area under the ROC curve (AUC) was over 0.81 in all cases, indicating from good to excellent model performance. Finally, examples of model applications in regulated sites were also presented in order to quantify the available habitat under specific environmental conditions and to define environmental flow standards. The meso-scale approach showed its potential in modelling habitat for fish and the presented statistical techniques can be considered a promising tool for river restoration and ecological management of Mediterranean streams.

  3. Hydrogeochemistry of the Overland Flow in Soil at Agroecosystems in Eastern Amazon

    Costa, C. F. G. D.; Figueiredo, R. O.; Oliveira, F. D. A.


    In the watershed of the Timboteua and Buiuna streams, northeast of Pará state, Amazon, it was characterized the overland flow dissolved material by some hydrogeochemical variables: electrical conductivity (EC), pH, chloride (Cl-), nitrate (NO3-), phosphate (PO43-), and sulfate (SO42-). In two small holder properties three overland flow experimental plots (1m2) were placed in each of the six evaluated ecosystems under similar biophysical conditions, totaling 18 plots. There was also installed three rainwater collectors and two rain gauges in a nearby area. In the rainy season were collected 234 samples of rainwater and overland flow. The evaluation of the measured variables promote the hydrogeochemical characterization of the overland flow at soil under chop-and-mulch and slash-and-burn practices in the different ecosystems found in the familiar agriculture of this watershed, in which it was identified some distinct hydrogeochemical characteristics of the overland flow. The lowest losses of NO3- (variation range = 0.07 to 2.57 μM) was found in agroecosystem - chop-and-mulch, this nutrient obtained higher values in agroecosystem - slash-and-burn (RQ). In agroecosystem (RQ) initially, there was a high value of PO43- (8.87 μM); EC (121 μS cm-1) and a subsequent sharp decline. Secondary successional forest (CP) of 20 years presented in overland flow pH 4.8 and EC 25 μS cm-1 (average 6 months), low loss of NO3- (0.2 μM) and PO43- (0.05 μM), and large range of variation of SO42- (0.7 to 21.5 μM). While Cl- and SO42- overland flow concentrations were affect by the rainfall variation, the increase of NO3- and PO43-concentrations were more related to the ecosystem management, with the first element responding to the presence of nitrogen-fixing species and the second responding to the burning practices. In summary: This study was efficient to characterize the hydrogeochemical of the overland flow and its relation to the altered ecosystems by Amazonian family farming.

  4. Regional Comparison of Nitrogen Export to Japanese Forest Streams

    Hideaki Shibata


    Full Text Available Nitrogen (N emissions in Asian countries are predicted to increase over the next several decades. An understanding of the mechanisms that control temporal and spatial fluctuation of N export to forest streams is important not only to quantify critical loads of N, N saturation status, and soil acidification N dynamics and budgets in Japanese forested watersheds is not clear due to the lack of regional comparative studies on stream N chemistry. To address the lack of comparative studies, we measured inorganic N (nitrate and ammonium concentrations from June 2000 to May 2001 in streams in 18 experimental forests located throughout the Japanese archipelago and belonging to the Japanese Union of University Forests. N concentrations in stream water during base flow and high flow periods were monitored, and N mineralization potential in soil was measured using batch incubation experiments. Higher nitrate concentrations in stream water were present in central Japan, an area that receives high rates of atmospheric N deposition. In northern Japan, snowmelt resulted in increased nitrate concentrations in stream water. The potential net N mineralization rate was higher in surface soil than in subsurface soil, and the high potential for N mineralization in the surface soil partly contributed to the increase in nitrate concentration in stream water during a storm event. Regional differences in the atmospheric N deposition and seasonality of precipitation and high discharge are principal controls on the concentrations and variations of nitrates in stream water in forested watersheds of Japan.

  5. Does unsaturated flow drive soil carbon residence times?

    Lawrence, C. R.; Mnich, M.; Druhan, J. L.; Schulz, M. S.; Stonestrom, D. A.; Maher, K.; Harden, J. W.


    Soil moisture is widely recognized as a driver of many important biogeochemical processes. For example, ecosystem productivity, microbial lifecycles, soil organic matter decomposition, soil secondary mineralogy, the development and persistence of redox gradients, and the export of dissolved carbon are all sensitive to soil-water content and potential. In turn, each of these processes is recognized as an important control on the turnover of soil organic carbon. These dependencies raise a key question: Is the flux of water through unsaturated soils the dominant driver of soil organic carbon turnover across broad spatial scales? To better characterize the importance of soil moisture fluxes, we synthesize data from a number of soil studies to evaluate how total soil carbon storage, carbon residence time, and depth dependent gradients vary in relation to soil hydrologic fluxes. Specifically, we compare soil carbon storage and stability to measured and/or modeled infiltration ([precipitation + condensation] - [evapotranspiration + runoff]) and long-term soil water flux estimates from chloride mass balance, or other techniques. Additionally, we consider the interaction of soil age and hydrology, as the development of secondary mineral horizons during pedogenesis represents a critical threshold in both soil water flux and soil organic carbon turnover. We focus on data from 3 previously descried soil chronosequences, including the Santa Cruz, Mattole, and Merced terraces, which together span a wide range of age and soil moisture conditions. Across these sites, organic carbon accumulates to greater depths in the soils with highest infiltration but the relationship between turnover and soil moisture is not as straightforward. To help interpret these results, we compare field data against simulations of biogeochemical reactions involving soil carbon and the resulting isotopic gradients using the reactive transport model CrunchTope. Overall, this effort provides for an improved

  6. Link between DOC in near surface peat and stream water in an upland catchment.

    Clark, Joanna M; Lane, Stuart N; Chapman, Pippa J; Adamson, John K


    Hydrologic transport of dissolved organic carbon (DOC) from peat soils may differ to organo-mineral soils in how they responded to changes in flow, because of differences in soil profile and hydrology. In well-drained organo-mineral soils, low flow is through the lower mineral layer where DOC is absorbed and high flow is through the upper organic layer where DOC is produced. DOC concentrations in streams draining organo-mineral soils typically increase with flow. In saturated peat soils, both high and low flows are through an organic layer where DOC is produced. Therefore, DOC in stream water draining peat may not increase in response to changes in flow as there is no switch in flow path between a mineral and organic layer. To verify this, we conducted a high-resolution monitoring study of soil and stream water at an upland peat catchment in northern England. Our data showed a strong positive correlation between DOC concentrations at -1 and -5 cm depth and stream water, and weaker correlations between concentrations at -20 to -50 cm depth and stream water. Although near surface organic material appears to be the key source of stream water DOC in both peat and organo-mineral soils, we observed a negative correlation between stream flow and DOC concentrations instead of a positive correlation as DOC released from organic layers during low and high flow was diluted by rainfall. The differences in DOC transport processes between peat and organo-mineral soils have different implications for our understanding of long-term changes in DOC exports. While increased rainfall may cause an increase in DOC flux from peat due to an increase in water volume, it may cause a decrease in concentrations. This response is contrary to expected changes in DOC exports from organo-mineral soils, where increase rainfall is likely to result in an increase in flux and concentration.

  7. Factors controlling soil water and stream water aluminum concentrations after a clearcut in a forested watershed with calcium-poor soils

    McHale, M.R.; Burns, Douglas A.; Lawrence, G.B.; Murdoch, Peter S.


    The 24 ha Dry Creek watershed in the Catskill Mountains of southeastern New York State USA was clearcut during the winter of 1996-1997. The interactions among acidity, nitrate (NO3- ), aluminum (Al), and calcium (Ca2+) in streamwater, soil water, and groundwater were evaluated to determine how they affected the speciation, solubility, and concentrations of Al after the harvest. Watershed soils were characterized by low base saturation, high exchangeable Al concentrations, and low exchangeable base cation concentrations prior to the harvest. Mean streamwater NO3- concentration was about 20 ??mol l-1 for the 3 years before the harvest, increased sharply after the harvest, and peaked at 1,309 ??mol l -1 about 5 months after the harvest. Nitrate and inorganic monomeric aluminum (Alim) export increased by 4-fold during the first year after the harvest. Alim mobilization is of concern because it is toxic to some fish species and can inhibit the uptake of Ca2+ by tree roots. Organic complexation appeared to control Al solubility in the O horizon while ion exchange and possibly equilibrium with imogolite appeared to control Al solubility in the B horizon. Alim and NO3- concentrations were strongly correlated in B-horizon soil water after the clearcut (r2 = 0.96), especially at NO3- concentrations greater than 100 ??mol l-1. Groundwater entering the stream from perennial springs contained high concentrations of base cations and low concentrations of NO3- which mixed with acidic, high Alim soil water and decreased the concentration of Alim in streamwater after the harvest. Five years after the harvest soil water NO 3- concentrations had dropped below preharvest levels as the demand for nitrogen by regenerating vegetation increased, but groundwater NO3- concentrations remained elevated because groundwater has a longer residence time. As a result streamwater NO3- concentrations had not fallen below preharvest levels, even during the growing season, 5 years after the harvest

  8. Regional statistical assessment of WRF-Hydro and IFC Model stream Flow uncertainties over the State of Iowa

    ElSaadani, M.; Quintero, F.; Goska, R.; Krajewski, W. F.; Lahmers, T.; Small, S.; Gochis, D. J.


    This study examines the performance of different Hydrologic models in estimating peak flows over the state of Iowa. In this study I will compare the output of the Iowa Flood Center (IFC) hydrologic model and WRF-Hydro (NFIE configuration) to the observed flows at the USGS stream gauges. During the National Flood Interoperability Experiment I explored the performance of WRF-Hydro over the state of Iowa using different rainfall products and the resulting hydrographs showed a "flashy" behavior of the model output due to lack of calibration and bad initial flows due to short model spin period. I would like to expand this study by including a second well established hydrologic model and include more rain gauge vs. radar rainfall direct comparisons. The IFC model is expected to outperform WRF-Hydro's out of the box results, however, I will test different calibration options for both the Noah-MP land surface model and RAPID, which is the routing component of the NFIE-Hydro configuration, to see if this will improve the model results. This study will explore the statistical structure of model output uncertainties across scales (as a function of drainage areas and/or stream orders). I will also evaluate the performance of different radar-based Quantitative Precipitation Estimation (QPE) products (e.g. Stage IV, MRMS and IFC's NEXRAD based radar rainfall product. Different basins will be evaluated in this study and they will be selected based on size, amount of rainfall received over the basin area and location. Basin location will be an important factor in this study due to our prior knowledge of the performance of different NEXRAD radars that cover the region, this will help observe the effect of rainfall biases on stream flows. Another possible addition to this study is to apply controlled spatial error fields to rainfall inputs and observer the propagation of these errors through the stream network.

  9. Environmental Geochemistry of Heavy Metal Contaminants in Soil and Stream Sediment in Panzhihua Mining and Smelting Area,Southwestern China

    滕彦国; 庹先国; 倪师军; 张成江; 徐争启


    Mining and smelting activities are the main causes for the increasing pollution ofheavy metals in soil, water body and stream sediment. An environmental geochemical investiga-tion was carried out in and around the Panzhihua mining and smelting area to determine the ex-tent of chemical contamination in soil and sediment. The main objective of this study was to in-vestigate the environmental geochemistry of Ti, V, Cr, Mn, Cu, Pb, Zn and As in soil andsediment and to assess the degree of pollution in the study area. The data of heavy metal con-centrations reveal that soils and sediments in the area have been slightly contaminated. Geo-chemical maps of Igeo of each heavy metal show that the contaminated sites are located in V-Ti-magnetite sloping and smelting, gangues dam. The pollution sources of the selected elementscome mainly from dusts resultant from mining activities and other three-waste-effluents. The areaneeds to be monitored regularly for trace metal, especially heavy metal enrichment.

  10. [Impact of rice agriculture on nitrogen and phosphorus exports in streams in hilly red soil earth region of central subtropics].

    Song, Li-Fang; Wang, Yi; Wu, Jin-Shui; Li, Yong; Li, Yu-Yuan; Meng, Cen; Li, Hang; Zhang, Man-Yi


    The research selected the Tuojia catchment and Jianshan catchment in Changsha County, Hunan Province, to comparatively study the effects of rice agriculture on the nitrogen and phosphorus concentrations and exports in streams in the typical agricultural catchments of the hilly red soil earth region. The monitoring of 16 months suggested that, there was a moderate stream nutrient pollution in both Tuojia and Jianshan catchments, especially for nitrogen pollution. Comparing the two catchments, the nitrogen and phosphorus concentrations were higher and the water quality was worse in the Tuojia catchment than that in the Jianshan catchment. From the nutrient composition of view, ammonia nitrogen was the main species of total nitrogen in the Tuojia catchment (accounting for 58.5% of total nitrogen), while it was nitrate nitrogen in the Jianshan catchment (accounting for 76. 1% of total nitrogen). The proportion of dissolved phosphorus in total phosphorus was 47. 1% in the Tuojia catchment, higher than the proportion of 37.5% in the Jianshan catchment. From temporal variations of nutrient dynamics of view, concentrations of all forms of nitrogen were higher during January to February and in July, respectively, and total phosphorus and dissolved phosphorus were higher during May to June and during October to December. Since the stream discharge in the catchments concentrated during the rice growing period from April to October, the higher nutrient concentrations during the period suggested potential risks of nitrogen and phosphorus losses. The total nitrogen mass flux was 1.67 kg x (hm2 x month)(-1) and TP was 0.06 kg x (hm2 x month)(-1) in the Tuojia catchment, which were greater than the 0.44 kg x (hm2 x month)(-1) and 0.02 kg x (hm2 x month)(-1) in the Jianshan catchment. Given the similar climate, geomorphology, soil type and cultivation patterns but the different area proportion of rice agriculture between two catchments, results suggested that, under the traditional

  11. A procedure for estimating Bacillus cereus spores in soil and stream-sediment samples - A potential exploration technique

    Watterson, J.R.


    The presence of bacterial spores of the Bacillus cereus group in soils and stream sediments appears to be a sensitive indicator of several types of concealed mineral deposits, including vein-type gold deposits. The B. cereus assay is rapid, inexpensive, and inherently reproducible. The test, currently under investigation for its potential in mineral exploration, is recommended for use on a research basis. Among the aerobic spore-forming bacilli, only B. cereus and closely related strains produce an opaque zone in egg-yolk emulsion agar. This characteristic, also known as the Nagler of lecitho-vitellin reaction, has long been used to rapidly indentify and estimate presumptive B. cereus. The test is here adapted to permit rapid estimation of B. cereus spores in soil and stream-sediment samples. Relative standard deviation was 10.3% on counts obtained from two 40-replicate pour-plate determinations. As many as 40 samples per day can be processed. Enough procedural detail is included to permit investigation of the test in conventional geochemical laboratories using standard microbiological safety precautions. ?? 1985.

  12. Instream flow characterization of Upper Salmon River basin streams, central Idaho, 2005

    Maret, Terry R.; Hortness, Jon E.; Ott, Douglas S.


    Anadromous fish populations in the Columbia River Basin have plummeted in the last 100 years. This severe decline led to Federal listing of Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (Oncorhynchus mykiss) stocks as endangered or threatened under the Endangered Species Act (ESA) in the 1990s. Historically, the upper Salmon River Basin (upstream of the confluence with the Pahsimeroi River) in Idaho provided migration corridors and significant habitat for these ESA-listed species, in addition to the ESA-listed bull trout (Salvelinus confluentus). Human development has modified the original streamflow conditions in many streams in the upper Salmon River Basin. Summer streamflow modifications resulting from irrigation practices, have directly affected quantity and quality of fish habitat and also have affected migration and (or) access to suitable spawning and rearing habitat for these fish. As a result of these ESA listings and Action 149 of the Federal Columbia River Power System Biological Opinion of 2000, the Bureau of Reclamation was tasked to conduct streamflow characterization studies in the upper Salmon River Basin to clearly define habitat requirements for effective species management and habitat restoration. These studies include collection of habitat and streamflow information for the Physical Habitat Simulation System (PHABSIM) model, a widely applied method to determine relations between habitat and discharge requirements for various fish species and life stages. Model simulation results can be used by resource managers to guide habitat restoration efforts by evaluating potential fish habitat and passage improvements by increasing or decreasing streamflow. In 2005, instream flow characterization studies were completed on Big Boulder, Challis, Bear, Mill, and Morgan Creeks. Continuous streamflow data were recorded upstream of all diversions on Big Boulder. Instantaneous measurements of discharge were also made at selected sites. In

  13. Identify temporal trend of air temperature and its impact on forest stream flow in Lower Mississippi River Alluvial Valley using wavelet analysis.

    Ouyang, Ying; Parajuli, Prem B; Li, Yide; Leininger, Theodor D; Feng, Gary


    Characterization of stream flow is essential to water resource management, water supply planning, environmental protection, and ecological restoration; while air temperature variation due to climate change can exacerbate stream flow and add instability to the flow. In this study, the wavelet analysis technique was employed to identify temporal trend of air temperature and its impact upon forest stream flows in Lower Mississippi River Alluvial Valley (LMRAV). Four surface water monitoring stations, which locate near the headwater areas with very few land use disturbances and the long-term data records (60-90 years) in the LMRAV, were selected to obtain stream discharge and air temperature data. The wavelet analysis showed that air temperature had an increasing temporal trend around its mean value during the past several decades in the LMRAV, whereas stream flow had a decreasing temporal trend around its average value at the same time period in the same region. Results of this study demonstrated that the climate in the LMRAV did get warmer as time elapsed and the streams were drier as a result of warmer air temperature. This study further revealed that the best way to estimate the temporal trends of air temperature and stream flow was to perform the wavelet transformation around their mean values. Published by Elsevier Ltd.

  14. MHD flow and heat transfer from continuous surface in uniform free stream of non-Newtonian fluid


    An analysis is carried out to study the steady flow and heat transfer characteristics from a continuous flat surface moving in a parallel free stream of an electrically conducting non-Newtonian viscoelastic fluid. The flow is subjected to a transverse uniform magnetic field. The constitutive equation of the fluid is modeled by that for a second grade fluid. Numerical results are obtained for the distribution of velocity and temperature profiles. The effects of various physical parameters like viscoelastic parameter, magnetic parameter and Prandtl number on various momentum and heat transfer characteristics are discussed in detail and shown graphically.


    Thomas Y. Hou; Brian R. Wetton


    Fourth-order stream-function methods are proposed for the time dependent, incom-pressible Navier-Stokes and Bonssinesq equations. Wide difference stencils are used instead of compact ones and the boundary terms are handled by extrapolating the stream-function values inside the computational domain to grid points outside, up to fourth-order in the no-slip condition. Formal error analysis is done for a simple model problem, showing that this extrapolation introduces numerical boundary layers at fifth-order in the stream-function. The fourth-order convergence in velocity of the proposed method for the full problem is shown numerically.

  16. Effects of land use and surficial geology on flow and water quality of streams in the coal-mining region of southwestern Indiana, October 1979 through September 1980

    Wilber, William G.; Renn, Danny E.; Crawford, Charles G.


    An assessment of streams in the coal-mining region of southwestern Indiana was done from October 1979 through September 1980 during stable stream flows to provide baseline hydrologic and water-quality information and to document the effect of several natural and human-induced factors on water quality in the region.

  17. Stream-flow forecasting using extreme learning machines: A case study in a semi-arid region in Iraq

    Yaseen, Zaher Mundher; Jaafar, Othman; Deo, Ravinesh C.; Kisi, Ozgur; Adamowski, Jan; Quilty, John; El-Shafie, Ahmed


    Monthly stream-flow forecasting can yield important information for hydrological applications including sustainable design of rural and urban water management systems, optimization of water resource allocations, water use, pricing and water quality assessment, and agriculture and irrigation operations. The motivation for exploring and developing expert predictive models is an ongoing endeavor for hydrological applications. In this study, the potential of a relatively new data-driven method, namely the extreme learning machine (ELM) method, was explored for forecasting monthly stream-flow discharge rates in the Tigris River, Iraq. The ELM algorithm is a single-layer feedforward neural network (SLFNs) which randomly selects the input weights, hidden layer biases and analytically determines the output weights of the SLFNs. Based on the partial autocorrelation functions of historical stream-flow data, a set of five input combinations with lagged stream-flow values are employed to establish the best forecasting model. A comparative investigation is conducted to evaluate the performance of the ELM compared to other data-driven models: support vector regression (SVR) and generalized regression neural network (GRNN). The forecasting metrics defined as the correlation coefficient (r), Nash-Sutcliffe efficiency (ENS), Willmott's Index (WI), root-mean-square error (RMSE) and mean absolute error (MAE) computed between the observed and forecasted stream-flow data are employed to assess the ELM model's effectiveness. The results revealed that the ELM model outperformed the SVR and the GRNN models across a number of statistical measures. In quantitative terms, superiority of ELM over SVR and GRNN models was exhibited by ENS = 0.578, 0.378 and 0.144, r = 0.799, 0.761 and 0.468 and WI = 0.853, 0.802 and 0.689, respectively and the ELM model attained lower RMSE value by approximately 21.3% (relative to SVR) and by approximately 44.7% (relative to GRNN). Based on the findings of this

  18. A Flow Model for the Settling Velocities of Non Spherical Particles in Creeping Motion. Part III. Slender Bodies, the Stream Functions, the Flow and the Momentum Equation

    Yuri Mendez


    Full Text Available This paper follows previous work regarding the settling velocity of non spherical particles in creeping motion. In this paper, we summarize the flow model, present solutions for the slender plate and the cylinder (Stoke’s paradox, demonstrate the application for euhedral pseudo hexagonal plates (KGa-1 and show the match to the experimental data. In addition, we derive the stream function for the sphere, the slender cylinder and the plate, develop the relationships to compute the flow about a settling particle, back calculate the momentum equation and examine the result

  19. Effects of land use and sample location on nitrate-stream flow hysteresis descriptors during storm events

    Feinson, Lawrence S.; Gibs, Jacob; Imbrigiotta, Thomas E.; Garrett, Jessica D.


    The U.S. Geological Survey's New Jersey and Iowa Water Science Centers deployed ultraviolet-visible spectrophotometric sensors at water-quality monitoring sites on the Passaic and Pompton Rivers at Two Bridges, New Jersey, on Toms River at Toms River, New Jersey, and on the North Raccoon River near Jefferson, Iowa to continuously measure in-stream nitrate plus nitrite as nitrogen (NO3 + NO2) concentrations in conjunction with continuous stream flow measurements. Statistical analysis of NO3 + NO2 vs. stream discharge during storm events found statistically significant links between land use types and sampling site with the normalized area and rotational direction of NO3 + NO2-stream discharge (N-Q) hysteresis patterns. Statistically significant relations were also found between the normalized area of a hysteresis pattern and several flow parameters as well as the normalized area adjusted for rotational direction and minimum NO3 + NO2 concentrations. The mean normalized hysteresis area for forested land use was smaller than that of urban and agricultural land uses. The hysteresis rotational direction of the agricultural land use was opposite of that of the urban and undeveloped land uses. An r2 of 0.81 for the relation between the minimum normalized NO3 + NO2 concentration during a storm vs. the normalized NO3 + NO2 concentration at peak flow suggested that dilution was the dominant process controlling NO3 + NO2 concentrations over the course of most storm events.

  20. Catchment disturbance and stream metabolism: Patterns in ecosystem respiration and gross primary production along a gradient of upland soil and vegetation disturbance

    Houser, J.N.; Mulholland, P.J.; Maloney, K.O.


    Catchment characteristics determine the inputs of sediments and nutrients to streams. As a result, natural or anthropogenic disturbance of upland soil and vegetation can affect instream processes. The Fort Benning Military Installation (near Columbus, Georgia) exhibits a wide range of upland disturbance levels because of spatial variability in the intensity of military training. This gradient of disturbance was used to investigate the effect of upland soil and vegetation disturbance on rates of stream metabolism (ecosystem respiration rate [ER] and gross primary production rate [GPP]). Stream metabolism was measured using an open-system, single-station approach. All streams were net heterotrophic during all seasons. ER was highest in winter and spring and lowest in summer and autumn. ER was negatively correlated with catchment disturbance level in winter, spring, and summer, but not in autumn. ER was positively correlated with abundance of coarse woody debris, but not significantly related to % benthic organic matter. GPP was low in all streams and generally not significantly correlated with disturbance level. Our results suggest that the generally intact riparian zones of these streams were not sufficient to protect them from the effect of upland disturbance, and they emphasize the role of the entire catchment in determining stream structure and function. ?? 2005 by The North American Benthological Society.


    Episodic acidification of streams, identified in the late 1980s as one of the most significant environmental problems caused by acidic deposition, had not been evaluated since the early 1990s despite decreasing levels of acidic deposition over the past decade. This analysis indic...


    Episodic acidification of streams, identified in the late 1980s as one of the most significant environmental problems caused by acidic deposition, had not been evaluated since the early 1990s despite decreasing levels of acidic deposition over the past decade. This analysis indic...

  3. Evaluating the use of drone photogrammetry for measurement of stream channel morphology and response to high flow events

    Price, Katie; Ballow, William


    great promise for the drone photogrammetry methods, which encouraged the exploration of the possibility of repeat aerial surveys to evaluate channel response to high flow events. Repeat drone surveys were performed following a sequence of high-flow events in Proctor Creek to evaluate the possibility of using these methods for assessment of stream channel response to flooding.

  4. Evaluation of probabilistic flow in two unsaturated soils

    Boateng, Samuel


    A variably saturated flow model is coupled to a first-order reliability algorithm to simulate unsaturated flow in two soils. The unsaturated soil properties are considered as uncertain variables with means, standard deviations, and marginal probability distributions. Thus, each simulation constitutes an unsaturated probability flow event. Sensitivities of the uncertain variables are estimated for each event. The unsaturated hydraulic properties of a fine-textured soil and a coarse-textured soil are used. The properties are based on the van Genuchten model. The flow domain has a recharge surface, a seepage boundary along the bottom, and a no-flow boundary along the sides. The uncertain variables are saturated water content, residual water content, van Genuchten model parameters alpha (α) and n, and saturated hydraulic conductivity. The objective is to evaluate the significance of each uncertain variable to the probabilistic flow. Under wet conditions, saturated water content and residual water content are the most significant uncertain variables in the sand. For dry conditions in the sand, however, the van Genuchten model parameters α and n are the most significant. Model parameter n and saturated hydraulic conductivity are the most significant for the wet clay loam. Saturated water content is most significant for the dry clay loam. Résumé. Un modèle d'écoulement variable en milieu saturé est couplé à un algorithme d'exactitude de premier ordre pour simuler les écoulements en milieu non saturé dans deux sols. Les propriétés des sols non saturés sont considérés comme des variables incertaines avec des moyennes, des écarts-types et des distributions de probabilité marginale. Ainsi chaque simulation constitue un événement d'écoulement non saturé probable. La sensibilité des variables incertaines est estimée pour chaque événement. Les propriétés hydrauliques non saturées d'un sol à texture fine et d'un sol à texture grossière sont utilis

  5. A Model of Debris Flow Forecast Based on the Water-Soil Coupling Mechanism

    Shaojie Zhang; Hongjuan Yang; Fangqiang Wei; Yuhong Jiang; Dunlong Liu


    Debris flow forecast is an important means of disaster mitigation. However, the accuracy of the statistics-based debris flow forecast is unsatisfied while the mechanism-based forecast is un-available at the watershed scale because most of existing researches on the initiation mechanism of de-bris flow took a single slope as the main object. In order to solve this problem, this paper developed a model of debris flow forecast based on the water-soil coupling mechanism at the watershed scale. In this model, the runoff and the instable soil caused by the rainfall in a watershed is estimated by the distrib-uted hydrological model (GBHM) and an instable identification model of the unsaturated soil. Because the debris flow is a special fluid composed of soil and water and has a bigger density, the density esti-mated by the runoff and instable soil mass in a watershed under the action of a rainfall is employed as a key factor to identify the formation probability of debris flow in the forecast model. The Jiangjia Gulley, a typical debris flow valley with a several debris flow events each year, is selected as a case study wa-tershed to test this forecast model of debris flow. According the observation data of Dongchuan Debris Flow Observation and Research Station, CAS located in Jiangjia Gulley, there were 4 debris flow events in 2006. The test results show that the accuracy of the model is satisfied.

  6. Enhancement of acoustic streaming induced flow on a focused surface acoustic wave device: Implications for biosensing and microfluidics

    Singh, Reetu; Sankaranarayanan, Subramanian K. R. S.; Bhethanabotla, Venkat R.


    the F-SAW device manifests itself as enhanced biofouling removal efficiency of F-SAW throughout the device delay path compared to the conventional device, thereby providing enhanced device sensitivity, selectivity, and reusability. Furthermore, contrary to the conventional SAW in which the smallest particle is removable near the input IDTs, the F-SAW device removes the smallest particle near the device focal point. The results of this work are shown to have significant implications in typical biosensing and microfluidic applications. In a broader context, the results of the present study demonstrate a technique of enhancing streaming induced flows, which is of great importance to contemporary problems involving microfluidic and sensing applications of piezoelectric devices.

  7. Subsurface flow in a soil-mantled subtropical dolomite karst slope: A field rainfall simulation study

    Fu, Z. Y.; Chen, H. S.; Zhang, W.; Xu, Q. X.; Wang, S.; Wang, K. L.


    Soil and epikarst co-evolve resulting in complex structures, but their coupled structural effects on hydrological processes are poorly understood in karst regions. This study examined the plot-scale subsurface flow characteristics from an integrated soil-epikarst system perspective in a humid subtropical cockpit karst region of Southwest China. A trench was excavated to the epikarst lower boundary for collecting individual subsurface flows in five sections with different soil thicknesses. Four field rainfall simulation experiments were carried out under different initial moisture conditions (dry and wet) and rainfall intensities (114 mm h- 1 (high) and 46 mm h- 1 (low) on average). The soil-epikarst system was characterized by shallow soil overlaying a highly irregular epikarst surface with a near-steady infiltration rate of about 35 mm h- 1. The subsurface flows occurred mainly along the soil-epikarst interface and were dominated by preferential flow. The subsurface flow hydrographs showed strong spatial variability and had high steady-state coefficients (0.52 and 0.36 for high and low rainfall intensity events). Irregular epikarst surface combining with high vertical drainage capacity resulted in high threshold rainfall depths for subsurface flows: 67 mm and 263 mm for initial wet and dry conditions, respectively. The above results evidenced that the irregular and permeable soil-epikarst interface was a crucial component of soil-epikarst architecture and consequently should be taken into account in the hydrological modeling for karst regions.

  8. CHNHYD: a channel hydrodynamic model for simulating flows and water surface elevations in a stream/river network

    Yeh, G.T.


    A description is given of the development of a channel hydrodynamic model for simulating the behavior of flows and water surface elevations in a river network that may consist of any number of joined and branched rivers/streams, including both tidal and nontidal rivers. The model employs a numerical method, an integrated compartment method (ICM). The basic procedures of the ICM are first to discretize the river/stream system into compartments of various sizes, then to apply three integral theorems of vectors to transform the n-dimensional volume integral into an (n - 1)-dimensional surface integral, and finally to close the system by using simple interpolation to relate the interfacial values in terms of the compartment values. Thus, the method greatly facilitates the setup of algebraic equations for the discrete field approximating the corresponding continuous field. Most of the possible boundary conditions that may be anticipated in real-world problems are considered. These include junctions, prescribed flow, prescribed water surface elevation (or cross-sectional area), and rating curve boundaries. The use of ICM makes the implementation of these four types of boundary conditions relatively easy. The model is applied to two case studies: first to a single river and then to a network of five river channels in a watershed. Results indicate that the model can definitely simulate the behavior of the hydrodynamic variables that are required to compute chemical transport in a river/stream network.

  9. Concentration-Gradient Multichannel Flow-Stream Membrane Capacitive Deionization Cell for High Desalination Capacity of Carbon Electrodes.

    Kim, Choonsoo; Lee, Juhan; Srimuk, Pattarachai; Aslan, Mesut; Presser, Volker


    We present a novel multichannel membrane flow-stream capacitive deionization (MC-MCDI) concept with two flow streams to control the environment around the electrodes and a middle channel for water desalination. The introduction of side channels to our new cell design allows operation in a highly saline environment, while the feed water stream in the middle channel (conventional CDI channel) is separated from the electrodes with anion- and cation-exchange membranes. At a high salinity gradient between side (1000 mm) and middle (5 mm) channels, MC-MCDI exhibited an unprecedented salt-adsorption capacity (SAC) of 56 mg g(-1) in the middle channel with charge efficiency close to unity and low energy consumption. This excellent performance corresponds to a fourfold increase in desalination performance compared to the state-of-the-art in a conventional CDI cell. The enhancement originates from the enhanced specific capacitance in high-molar saline media in agreement with the Gouy-Chapman-Stern theory and from a double-ion desorption/adsorption process of MC-MCDI through voltage operation from -1.2 to +1.2 V. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Dam metrics representing stream fragmentation and flow alteration for the conterminous United States linked to the NHDPLUSV1

    Cooper, Arthur R.; Infante, Dana M.


    This CSV file contains 21 dam metrics representing stream fragmentation and flow alteration for nearly 2.3 million stream reaches in the conterminous USA. Dam metrics fall into four main categories: segment-based, count and density, distance-based, and cumulative reservoir storage (described below). These data were developed using spatially verified large dam locations (n=49,468) primarily from the National Anthropogenic Barrier Dataset (NABD) that were spatially linked to the National Hydrography Dataset Plus version 1 (NHDPlusV1). These dam metrics have been summarized using the unique identifier field native to the NHDPlusV1 (COMID) which can be used to join this table to spatial layers and data tables of the NHDPlusV1. Non-fluvial features in the NHDPlusV1 (lake and reservoir flow paths, coastlines, etc.) are excluded (see NFHP metadata). Please contact Arthur Cooper ( for a copy of the publication associated with this data: Cooper, A.R., Infante, D.M., Daniel, W.M., Wehrly, K.E., Wang, L., Brenden, T.O. 2017. Assessment of dam effects for streams and fish assemblages of the conterminous USA. Science of the Total Environment doi:10.1016/j.scitotenv.2017.02.067

  11. Unsaturated flow processes in structurally-variable pathways in wildfire-affected soils and ash

    Ebel, B. A.


    Prediction of flash flood and debris flow generation in wildfire-affected soils and ash hinges on understanding unsaturated flow processes. Water resources issues, such as groundwater recharge, also rely on our ability to quantify subsurface flow. Soil-hydraulic property data provide insight into unsaturated flow processes and timescales. A literature review and synthesis of existing data from the literature for wildfire-affected soils, including ash and unburned soils, facilitated calculating metrics and timescales of hydrologic response related to infiltration and surface runoff generation. Sorptivity (S) and the Green-Ampt wetting front parameter (Ψf) were significantly lower in burned soils compared to unburned soils, while field-saturated hydraulic conductivity (Kfs) was not significantly different. The magnitude and duration of the influence of capillarity was substantially reduced in burned soils, leading to faster ponding times in response to rainfall. Ash had large values of S and Kfs compared to unburned and burned soils but intermediate values of Ψf, suggesting that ash has long ponding times in response to rainfall. The ratio of S2/Kfs was nearly constant ( 100 mm) for unburned soils, but was more variable in burned soils. Post-wildfire changes in this ratio suggested that unburned soils had a balance between gravity and capillarity contributions to infiltration, which may depend on soil organic matter, while burning shifted infiltration more towards gravity contributions by reducing S. Taken together, the changes in post-wildfire soil-hydraulic properties increased the propensity for surface runoff generation and may have enhanced subsurface preferential flow through pathways altered by wildfire.

  12. Nonequilibrium water dynamics in the rhizosphere: How mucilage affects water flow in soils

    Kroener, Eva; Zarebanadkouki, Mohsen; Kaestner, Anders; Carminati, Andrea


    The flow of water from soil to plant roots is controlled by the properties of the narrow region of soil close to the roots, the rhizosphere. In particular, the hydraulic properties of the rhizosphere are altered by mucilage, a polymeric gel exuded by the roots. In this paper we present experimental results and a conceptual model of water flow in unsaturated soils mixed with mucilage. A central hypothesis of the model is that the different drying/wetting rate of mucilage compared to the bulk soil results in nonequilibrium relations between water content and water potential in the rhizosphere. We coupled this nonequilibrium relation with the Richards equation and obtained a constitutive equation for water flow in soil and mucilage. To test the model assumptions, we measured the water retention curve and the saturated hydraulic conductivity of sandy soil mixed with mucilage from chia seeds. Additionally, we used neutron radiography to image water content in a layer of soil mixed with mucilage during drying and wetting cycles. The radiographs demonstrated the occurrence of nonequilibrium water dynamics in the soil-mucilage mixture. The experiments were simulated by numerically solving the nonequilibrium model. Our study provides conceptual and experimental evidences that mucilage has a strong impact on soil water dynamics. During drying, mucilage maintains a greater soil water content for an extended time, while during irrigation it delays the soil rewetting. We postulate that mucilage exudation by roots attenuates plant water stress by modulating water content dynamics in the rhizosphere.

  13. Low-flow frequency and flow duration of selected South Carolina streams in the Savannah and Salkehatchie River Basins through March 2014

    Feaster, Toby D.; Guimaraes, Wladmir B.


    An ongoing understanding of streamflow characteristics of the rivers and streams in South Carolina is important for the protection and preservation of the State’s water resources. Information concerning the low-flow characteristics of streams is especially important during critical flow periods, such as during the historic droughts that South Carolina has experienced in the past few decades.In 2008, the U.S. Geological Survey, in cooperation with the South Carolina Department of Health and Environmental Control, initiated a study to update low-flow statistics at continuous-record streamgaging stations operated by the U.S. Geological Survey in South Carolina. This report presents the low-flow statistics for 28 selected streamgaging stations in the Savannah and Salkehatchie River Basins in South Carolina. The low-flow statistics include daily mean flow durations for the 5-, 10-, 25-, 50-, 75-, 90-, and 95-percent probability of exceedance and the annual minimum 1-, 3-, 7-, 14-, 30-, 60-, and 90-day mean flows with recurrence intervals of 2, 5, 10, 20, 30, and 50 years, depending on the length of record available at the streamgaging station. The low-flow statistics were computed from records available through March 31, 2014.Low-flow statistics are influenced by length of record, hydrologic regime under which the data were collected, analytical techniques used, and other factors, such as urbanization, diversions, and droughts that may have occurred in the basin. To assess changes in the low-flow statistics from the previously published values, a comparison of the low-flow statistics for the annual minimum 7-day average streamflow with a 10-year recurrence interval (7Q10) from this study was made with the most recently published values. Of the 28 streamgaging stations for which recurrence interval computations were made, 14 streamgaging stations were suitable for comparing to low-flow statistics that were previously published in U.S. Geological Survey reports. These

  14. Low-flow frequency and flow duration of selected South Carolina streams in the Catawba-Wateree and Santee River Basins through March 2012

    Feaster, Toby D.; Guimaraes, Wladmir B.


    Part of the mission of both the South Carolina Department of Health and Environmental Control and the South Carolina Department of Natural Resources is to protect and preserve South Carolina’s water resources. Doing so requires an ongoing understanding of streamflow characteristics of the rivers and streams in South Carolina. A particular need is information concerning the low-flow characteristics of streams, which is especially important for effectively managing the State’s water resources during critical flow periods, such as during the historic droughts that South Carolina has experienced in the past few decades. In 2008, the U.S. Geological Survey, in cooperation with the South Carolina Department of Health and Environmental Control, initiated a study to update low-flow statistics at continuous-record streamgaging stations operated by the U.S. Geological Survey in South Carolina. This report presents the low-flow statistics for 11 selected streamgaging stations in the Catawba-Wateree and Santee River Basins in South Carolina and 2 in North Carolina. For five of the streamgaging stations, low-flow statistics include daily mean flow durations or the 5-, 10-, 25-, 50-, 75-, 90-, and 95-percent probability of exceedance and the annual minimum 1-, 3-, 7-, 14-, 30-, 60-, and 90-day mean flows with recurrence intervals of 2, 5, 10, 20, 30, and 50 years, depending on the length of record available at the streamgaging station. For the other eight streamgaging stations, only daily mean flow durations and (or) exceedance percentiles of annual minimum 7-day average flows are provided due to regulation. In either case, the low-flow statistics were computed from records available through March 31, 2012. Of the five streamgaging stations for which recurrence interval computations were made, three streamgaging stations in South Carolina were compared to low-flow statistics that were published in previous U.S. Geological Survey reports. A comparison of the low-flow

  15. System and method for measuring particles in a sample stream of a flow cytometer using a low power laser source

    Graves, Steven W; Habbersett, Robert C


    A system and method for analyzing a particle in a sample stream of a flow cytometer or the like. The system has a light source, such as a laser pointer module, for generating a low powered light beam and a fluidics apparatus which is configured to transport particles in the sample stream at substantially low velocity through the light beam for interrogation. Detectors, such as photomultiplier tubes, are configured to detect optical signals generated in response to the light beam impinging the particles. Signal conditioning circuitry is connected to each of the detectors to condition each detector output into electronic signals for processing and is designed to have a limited frequency response to filter high frequency noise from the detector output signals.

  16. System and method for measuring particles in a sample stream of a flow cytometer or the like

    Graves, Steven W. (San Juan Pueblo, NM); Habberset, Robert C. (Santa Fe, NM)


    A system and method for analyzing a particle in a sample stream of a flow cytometer or the like. The system has a light source, such as a laser pointer module, for generating a low powered light beam and a fluidics apparatus which is configured to transport particles in the sample stream at substantially low velocity through the light beam for interrogation. Detectors, such as photomultiplier tubes, are configured to detect optical signals generated in response to the light beam impinging the particles. Signal conditioning circuitry is connected to each of the detectors to condition each detector output into electronic signals for processing and is designed to have a limited frequency response to filter high frequency noise from the detector output signals.

  17. System and method for measuring particles in a sample stream of a flow cytometer using low-power laser source

    Graves, Steven W.; Habbersett, Robert C.


    A system and method for analyzing a particle in a sample stream of a flow cytometer or the like. The system has a light source, such as a laser pointer module, for generating a low powered light beam and a fluidics apparatus which is configured to transport particles in the sample stream at substantially low velocity through the light beam for interrogation. Detectors, such as photomultiplier tubes, are configured to detect optical signals generated in response to the light beam impinging the particles. Signal conditioning circuitry is connected to each of the detectors to condition each detector output into electronic signals for processing and is designed to have a limited frequency response to filter high frequency noise from the detector output signals.

  18. Scaling and pedotransfer in numerical simulations of flow and transport in soils

    Flow and transport parameters of soils in numerical simulations need to be defined at the support scale of computational grid cells. Such support scale can substantially differ from the support scale in laboratory or field measurements of flow and transport parameters. The scale-dependence of flow a...

  19. Functional behaviour of pedotransfer functions in soil water flow simulation

    Soet, M.; Stricker, J.N.M.


    Soil hydraulic parameter values for large-scale modelling cannot be obtained by direct methods. Pedotransfer functions (PTFs) that relate soil hydraulic properties (SHPs) to generally available soil texture data may provide an alternative. A considerable number of PTF models has been developed, the

  20. Combined role of molecular diffusion, mean streaming and helicity in the eddy diffusivity of short-correlated random flows

    Afonso, Marco Martins; Gama, Sílvio


    We analytically investigate the effective-diffusivity tensor of a tracer particle in a fluid flow endowed with a short correlation time. By means of functional calculus and a multiscale expansion, we write down the main contributions to the eddy diffusivity due to each single physical effect and to their interplays. Namely, besides molecular diffusivity and a constant uniform mean streaming, we take into account the possibility for the (incompressible, Gaussian, stationary, homogeneous, isotropic) turbulent fluctuations to break parity invariance. With respect to the classical turbulence-driven diffusivity amplification for delta-correlated flows, we find that the presence of a short temporal correlation induces a diminution even when coupled with such effects, with two principal exceptions. Notably, the diffusivity is --- perturbatively --- enlarged not only by the helical contribution itself, but also by the interference between molecular diffusion and mean flow.

  1. Association of Dissolved Mercury with Dissolved Organic Carbon in Rivers and Streams: The Role of Watershed Soil Organic Carbon

    Stoken, O.; Riscassi, A.; Scanlon, T. M.


    Surface waters are an important pathway for the transport of atmospherically deposited mercury (Hg) from terrestrial watersheds. Dissolved Hg (HgD) is thought to be more bioavailable than particulate Hg and has been found to be strongly correlated with dissolved organic carbon (DOC) in numerous watersheds. The ratio of HgD to DOC is highly variable from site to site, which we hypothesize is strongly dependent on local environmental factors such as atmospheric deposition and soil organic carbon (SOC). Sixteen watersheds throughout the United States were used in this study to determine the relationship between the ratio of HgD:DOC, Hg wet deposition, and SOC. The Soil Survey Geographic database (SSURGO) and Northern Circumpolar Soil Carbon Database (NCSCD) were used to determine SOC values while HgD:DOC values were obtained from previous studies. Hg wet deposition was reported by the Mercury Deposition Network. There was no correlation found between atmospheric mercury wet deposition and HgD:DOC (r2 = 0.04; p = 0.44) but SOC was able to explain about 71% of the variation in the HgD:DOC ratio (r2 = 0.71; p Hg adsorbed to SOC does not increase in proportion to SOC at high SOC levels and points towards a Hg supply limitation for adsorption to soils with relatively deep carbon pools. Overall, this study identifies SOC as a first-order control on the association of HgD and DOC and indicates that globally available SOC datasets can be utilized to predict Hg transport in stream systems.

  2. Impact of climate change on the stream flow of lower Brahmaputra: trends in high and low flows based on discharge- weighted ensemble modelling

    A. K. Gain


    Full Text Available Climate change is likely to have significant effects on the hydrology. The Ganges-Brahmaputra river basin is one of the most vulnerable areas in the world as it is subject to the combined effects of glacier melt, extreme monsoon rainfall and sea level rise. To what extent climate change will impact river flow in the Brahmaputra basin is yet unclear, as climate model studies show ambiguous results. In this study we investigate the effect of climate change on both low and high flows of the lower Brahmaputra. We apply a novel method of discharge-weighted ensemble modeling using model outputs from a global hydrological models forced with 12 different global climate models (GCMs. Based on the GCM outputs and long-term records of observed flow at Bahadurabad station, our method results in a multi-model weighted ensemble of transient stream flow for the period 1961–2100. Using the constructed transients, we subsequently project future trends in low and high river flow. The analysis shows that extreme low flow conditions are likely to occur less frequent in the future. However a very strong increase in peak flows is projected, which may, in combination with projected sea level change, have devastating effects for Bangladesh. The methods presented in this study are more widely applicable, in that existing multi-model streamflow simulations from global hydrological models can be weighted against observed streamflow data to assess at first order the effects of climate change for specific river basins.

  3. Estimating glacier and snowmelt contributions to stream flow in a Central Andes catchment in Chile using natural tracers

    M. Rodriguez


    Full Text Available This paper presents a methodology for hydrograph separation in high elevation watersheds, which aims at identifying individual flow sources such as snow- and ice melt, rainfall and soil water. Daily summer and bi-daily spring water samples from the outlet of the Juncal River were analyzed for all major ions as well as stable water isotopes, δ18O and δ2H. Additionally, various water sources such as rain, springs, snow- and glacial melt were sampled throughout the catchment. A principal component analysis (PCA was performed in order to reduce the dimensionality of the problem. Potential sources were identified in a two-component U space that explains 77% of variability. Hydrograph separation (HS was performed through three models: (i Isotopic model, (ii Mixing–PCA model, and (iii Informative–Bayesian model, with very similar results in each case. At the Juncal River outlet, summer flows were composed by at least 50% of water originating in highly glaciarized headwaters in 2011–2012 (a dry period in the Central Andes. Autumn and winter flows were highly influenced by soil water and affect total annual discharge. Before the high flow season, snow melt accounted for approximately 25% of streamflow, However during summer, when streamflow was highest, snowmelt contribution was minimal, while glacier melt and soil water were the most important sources.

  4. Development of a stream-aquifer numerical flow model to assess river water management under water scarcity in a Mediterranean basin

    Mas-Pla, Josep, E-mail: [Grup de Geologia Aplicada i Ambiental (GAiA), Centre de Geologia i Cartografia Ambiental (Geocamb), Dept. de Ciencies Ambientals, Universitat de Girona (Spain); Font, Eva [Grup de Geologia Aplicada i Ambiental (GAiA), Centre de Geologia i Cartografia Ambiental (Geocamb), Dept. de Ciencies Ambientals, Universitat de Girona (Spain); Astui, Oihane [Agencia Catalana de l' Aigua, Barcelona (Spain); Mencio, Anna; Rodriguez-Florit, Agusti [Grup de Geologia Aplicada i Ambiental (GAiA), Centre de Geologia i Cartografia Ambiental (Geocamb), Dept. de Ciencies Ambientals, Universitat de Girona (Spain); Folch, Albert [Unitat de Geodinamica Externa i Hidrogeologia Dept. de Geologia, Universitat Autonoma of Barcelona (Spain); Brusi, David [Grup de Geologia Aplicada i Ambiental (GAiA), Centre de Geologia i Cartografia Ambiental (Geocamb), Dept. de Ciencies Ambientals, Universitat de Girona (Spain); Perez-Paricio, Alfredo [Agencia Catalana de l' Aigua, Barcelona (Spain)


    Stream flow, as a part of a basin hydrological cycle, will be sensible to water scarcity as a result of climate change. Stream vulnerability should then be evaluated as a key component of the basin water budget. Numerical flow modeling has been applied to an alluvial formation in a small mountain basin to evaluate the stream-aquifer relationship under these future scenarios. The Arbucies River basin (116 km{sup 2}) is located in the Catalan Inner Basins (NE Spain) and its lower reach, which is related to an alluvial aquifer, usually becomes dry during the summer period. This study seeks to determine the origin of such discharge losses whether from natural stream leakage and/or induced capture due to groundwater withdrawal. Our goal is also investigating how discharge variations from the basin headwaters, representing potential effects of climate change, may affect stream flow, aquifer recharge, and finally environmental preservation and human supply. A numerical flow model of the alluvial aquifer, based on MODFLOW and especially in the STREAM routine, reproduced the flow system after the usual calibration. Results indicate that, in the average, stream flow provides more than 50% of the water inputs to the alluvial aquifer, being responsible for the amount of stored water resources and for satisfying groundwater exploitation for human needs. Detailed simulations using daily time-steps permit setting threshold values for the stream flow entering at the beginning of the studied area so surface discharge is maintained along the whole watercourse and ecological flow requirements are satisfied as well. The effects of predicted rainfall and temperature variations on the Arbucies River alluvial aquifer water balance are also discussed from the outcomes of the simulations. Finally, model results indicate the relevance of headwater discharge management under future climate scenarios to preserve downstream hydrological processes. They also point out that small mountain basins

  5. Cryptic flows: using multiple tracers to relate dissolved oxygen to hyporheic and groundwater flowpaths in intermittent salmonid streams

    Woelfle-Erskine, C. A.; Larsen, L.; Gomez-Velez, J. D.


    Intermittent streams provide important habitat for aquatic species, including endangered salmonid fishes, but during prolonged dry periods may become depleted in dissolved oxygen (DO). The rate of depletion and the consequent length of time a pool remains habitable depend on DO and carbon concentrations in groundwater and hyporheic flow, and within-pool metabolic rates. We performed repeat surveys, habitat characterization, and ecohydrologic sampling on two intermittent tributaries of Salmon Creek (Sonoma Co., CA) to elucidate controls on salmonid over-summer survival at the pool scale. Pools exhibited heterogeneity within and across stream reaches in salmonid recruitment and survival during the summer dry period. In classification tree analysis, high conductivity (>310 mS/cm) and low DO (concentration. To distinguish between surface, hyporheic, and groundwater contributions, we measured dissolved organic carbon (DOC) concentration and fluorescence excitation-emission matrices (EEMs), radon (222Rn), and stable isotopes (18O and D) in pools, hyporheic flow, and wells and springs in local aquifers. Radon concentrations in pools ranged from 1.5-2.3 Bq/l, 3-4 orders of magnitude higher than expected for water in equilibrium with air, suggesting substantial groundwater inflow. We developed a five-component PARAFAC model from the EEMs and used with the isotope data to perform an end-member mixing analysis to track water sources and flowpaths. These analyses suggested high separability among groundwaters from aquifers separated by faults and between groundwater and surface water, with groundwater of different age and flowpath length discharging to different pools. Pools with shallow groundwater or hyporheic flow sustained DO concentrations above the threshold for salmonid survival, with shallow groundwater unexpectedly acting as a source of DO to the stream. These inflows were further essential for inhibiting stagnation and promoting reaeration across the air

  6. Paper-based enzymatic microfluidic fuel cell: From a two-stream flow device to a single-stream lateral flow strip

    González-Guerrero, Maria José; del Campo, F. Javier; Esquivel, Juan Pablo; Giroud, Fabien; Minteer, Shelley D.; Sabaté, Neus


    This work presents a first approach towards the development of a cost-effective enzymatic paper-based glucose/O2 microfluidic fuel cell in which fluid transport is based on capillary action. A first fuel cell configuration consists of a Y-shaped paper device with the fuel and the oxidant flowing in parallel over carbon paper electrodes modified with bioelectrocatalytic enzymes. The anode consists of a ferrocenium-based polyethyleneimine polymer linked to glucose oxidase (GOx/Fc-C6-LPEI), while the cathode contains a mixture of laccase, anthracene-modified multiwall carbon nanotubes, and tetrabutylammonium bromide-modified Nafion (MWCNTs/laccase/TBAB-Nafion). Subsequently, the Y-shaped configuration is improved to use a single solution containing both, the anolyte and the catholyte. Thus, the electrolytes pHs of the fuel and the oxidant solutions are adapted to an intermediate pH of 5.5. Finally, the fuel cell is run with this single solution obtaining a maximum open circuit of 0.55 ± 0.04 V and a maximum current and power density of 225 ± 17 μA cm-2 and 24 ± 5 μW cm-2, respectively. Hence, a power source closer to a commercial application (similar to conventional lateral flow test strips) is developed and successfully operated. This system can be used to supply the energy required to power microelectronics demanding low power consumption.

  7. Application of a GIS-based distributed hydrology model for prediction of forest harvest effects on peak stream flow in the Pacific Northwest

    Storck, Pascal; Bowling, Laura; Wetherbee, Paul; Lettenmaier, Dennis


    Spatially distributed rainfall-runoff models, made feasible by the widespread availability of land surface characteristics data (especially digital topography), and the evolution of high power desktop workstations, are particularly useful for assessment of the hydrological effects of land surface change. Three examples are provided of the use of the Distributed Hydrology-Soil-Vegetation Model (DHSVM) to assess the hydrological effects of logging in the Pacific Northwest. DHSVM provides a dynamic representation of the spatial distribution of soil moisture, snow cover, evapotranspiration and runoff production, at the scale of digital topographic data (typically 30-100 m). Among the hydrological concerns that have been raised related to forest harvest in the Pacific Northwest are increases in flood peaks owing to enhanced rain-on-snow and spring radiation melt response, and the effects of forest roads. The first example is for two rain-on-snow floods in the North Fork Snoqualmie River during November 1990 and December 1989. Predicted maximum vegetation sensitivities (the difference between predicted peaks for all mature vegetation compared with all clear-cut) showed a 31% increase in the peak runoff for the 1989 event and a 10% increase for the larger 1990 event. The main reason for the difference in response can be traced to less antecedent low elevation snow during the 1990 event. The second example is spring snowmelt runoff for the Little Naches River, Washington, which drains the east slopes of the Washington Cascades. Analysis of spring snowmelt peak runoff during May 1993 and April 1994 showed that, for current vegetation relative to all mature vegetation, increases in peak spring stream flow of only about 3% should have occurred over the entire basin. However, much larger increases (up to 30%) would occur for a maximum possible harvest scenario, and in a small headwaters catchment, whose higher elevation leads to greater snow coverage (and, hence, sensitivity

  8. Leaf Degradation, Macroinvertebrate Shredders & Energy Flow in Streams: A Laboratory-Based Exercise Examining Ecosystem Processes

    Sparkes, Timothy C.; Mills, Colleen M.; Volesky, Lisa; Talkington, Jennifer; Brooke, Joanna


    A laboratory-based exercise that demonstrates mechanisms underlying leaf degradation in streams. Students examine the effects of "leaf conditioning" on the feeding behavior of invertebrate shredders. The exercise is completed in two sessions and can be adapted to both high school and college levels.

  9. Management of surface water and groundwater withdrawals to maintain environmental stream flows in Michigan

    Reeves, Howard W.; Seelbach, Paul W.; Nicholas, James R.; Hamilton, David A.; Potter, Kenneth W.; Frevert, Donald K.


    In 2008, the State of Michigan enacted legislation requiring that new or increased high-capacity withdrawals (greater than 100,000 gallons per day) from either surface water or groundwater be reviewed to prevent Adverse Resource Impacts (ARI). Science- based guidance was sought in defining how groundwater or surface-water withdrawals affect streamflow and in quantifying the relation between reduced streamflow and changes in stream ecology. The implementation of the legislation led to a risk-based system based on a gradient of risk, ecological response curves, and estimation of groundwater-surface water interaction. All Michigan streams are included in the legislation, and, accordingly, all Michigan streams were classified into management types defined by size of watershed, stream-water temperature, and predicted fish assemblages. Different streamflow removal percentages define risk-based thresholds allowed for each type. These removal percentages were informed by ecological response curves of characteristic fish populations and finalized through a legislative workgroup process. The assessment process includes an on-line screening tool that may be used to evaluate new or increased withdrawals against the risk-based zones and allows withdrawals that are not likely to cause an ARI to proceed to water-use registration. The system is designed to consider cumulative impacts of high-capacity withdrawals and to promote user involvement in water resource management by the establishment of water-user committees as cumulative withdrawals indicate greater potential for ARI in the watershed.

  10. Best practices for continuous monitoring of temperature and flow in wadeable streams

    Jen Stamp; Anna Hamilton; Michelle Craddock; Laila Parker; Allison H. Roy; Daniel J. Isaak; Zach Holden; Margaret Passmore; Britta G. Bierwagen


    The United States Environmental Protection Agency (U.S. EPA) is working with its regional offices, states, tribes, river basin commissions and other entities to establish Regional Monitoring Networks (RMNs) for freshwater wadeable streams. To the extent possible, uninterrupted, biological, temperature and hydrologic data will be collected on an ongoing basis at RMN...

  11. Photo-nucleation theory of correlation of Stream-flow of four South American rivers with Sunspot Cycle

    Brown, W Byers


    C.T.R.Wilson showed that when supersaturated water vapour was exposed to ultraviolet radiation from sunlight or other sources in the presence of oxygen it immediately condensed to form an aerosol. This phenomenon was eventually explained as due to the formation of a charge-transfer complex H2O+O2-, whose existence was confirmed theoretically and subsequently established experimentally. It is proposed that the correlation recently discovered between the stream-flow of the Parana and three other rivers in South America and the solar sunspot cycle is due to the photo-nucleation mechanism investigated by Wilson.

  12. Analysis of low flows and selected methods for estimating low-flow characteristics at partial-record and ungaged stream sites in western Washington

    Curran, Christopher A.; Eng, Ken; Konrad, Christopher P.


    A regional low-flow survey of small, perennial streams in western Washington was initiated by the Northwest Indian Fisheries Commission (NWIFC), NWIFC-member tribes, and Point-No-Point Treaty Council in cooperation with the U.S. Geological Survey in 2007 and repeated by the tribes during the low-flow seasons of 2008–09. Low-flow measurements at 63 partial-record and miscellaneous streamflow-measurement sites during surveys in 2007–09 are used with concurrent flows at continuous streamflow-gaging stations (index sites) within the U.S. Geological Survey network to estimate the low-flow metric Q7,10 at each measurement site (Q7,10 is defined as the lowest average streamflow for a consecutive 7-day period that recurs on average once every 10 years). Index-site correlation methods for estimating low-flow characteristics at partial-record sites are reviewed and an empirical Monte Carlo technique is used with the daily streamflow record at 43 index sites to determine the error and bias associated with estimating the Q7,10 at synthetic partial-record sites using three methods: Q-ratio, MOVE.1, and Base-Flow Correlation. The Q-ratio method generally has the lowest error and least amount of bias for 170 scenarios, with each scenario defined by the number of concurrent flow measurements between the partial-record and index sites (ranging from 4 to 20) and the combination of basin attributes used to select the index site. The root-mean square error for the Q-ratio method ranged from 70 to 118 percent, depending on the scenario. The scenario with the smallest root-mean square error used four concurrent flow measurements and the basin attributes: basin area, mean annual precipitation, and base-flow recession time constant, also referred to as tau (τ).

  13. Modelling mean transit time of stream base flow during tropical cyclone rainstorm in a steep relief forested catchment

    Lee, Jun-Yi; Huang, -Chuan, Jr.


    Mean transit time (MTT) is one of the of fundamental catchment descriptors to advance understanding on hydrological, ecological, and biogeochemical processes and improve water resources management. However, there were few documented the base flow partitioning (BFP) and mean transit time within a mountainous catchment in typhoon alley. We used a unique data set of 18O isotope and conductivity composition of rainfall (136 mm to 778 mm) and streamflow water samples collected for 14 tropical cyclone events (during 2011 to 2015) in a steep relief forested catchment (Pinglin, in northern Taiwan). A lumped hydrological model, HBV, considering dispersion model transit time distribution was used to estimate total flow, base flow, and MTT of stream base flow. Linear regression between MTT and hydrometric (precipitation intensity and antecedent precipitation index) variables were used to explore controls on MTT variation. Results revealed that both the simulation performance of total flow and base flow were satisfactory, and the Nash-Sutcliffe model efficiency coefficient of total flow and base flow was 0.848 and 0.732, respectively. The event magnitude increased with the decrease of estimated MTTs. Meanwhile, the estimated MTTs varied 4-21 days with the increase of BFP between 63-92%. The negative correlation between event magnitude and MTT and BFP showed the forcing controls the MTT and BFP. Besides, a negative relationship between MTT and the antecedent precipitation index was also found. In other words, wetter antecedent moisture content more rapidly active the fast flow paths. This approach is well suited for constraining process-based modeling in a range of high precipitation intensity and steep relief forested environments.

  14. The preferential flow of soil: A widespread phenomenon in pedological perspectives

    Zhang, Yinghu; Zhang, Mingxiang; Niu, Jianzhi; Zheng, Haijin


    The article provides an overview of studies about the preferential flow phenomenon. This phenomenon is one of the types of the transportation of water solution through the soil profile by preferential channels (pathways) with a relatively high speed and with a slight change in the chemical composition of the solution. Interest in this phenomenon has risen sharply in the last two decades due to the observed fast transportation of contaminants from soil surface into groundwater level. On the basis of the literature data, the authors give the definition of this phenomenon, consider its types, degree, features, mechanisms, methods and models and research perspectives, in particular the interaction between preferential flow and soil matrix flow. The article considers the aspects of the movement of soil water carrying heavy metals and pesticides; hence, it concerns the protection of environment and people's health. It provides the thorough review of the studies on the preferential flow, and describes the research directions and their development.

  15. Low-flow frequency and flow duration of selected South Carolina streams in the Broad River basin through March 2008

    Guimaraes, Wladmir B.; Feaster, Toby D.


    In 2008, the U.S. Geological Survey, in cooperation with the South Carolina Department of Health and Environmental Control, initiated a study to update low-flow statistics at continuous-record streamgaging stations operated by the U.S. Geological Survey in South Carolina. This report presents the low-flow statistics for 23 selected streamgaging stations in the Broad River basin in South Carolina, and includes flow durations of 5-, 10-, 25-, 50-, 75-, 90-, and 95-percent probability of exceedance and the annual minimum 1-, 3-, 7-, 14-, 30-, 60-, and 90-day mean flows with recurrence intervals of 2, 5, 10, 20, 30, and 50 years, depending on the length of record available at the streamgaging station. The low-flow statistics were computed from records available through March 31, 2008. In addition, flow duration information is presented for one streamgaging station 021556525, Pacolet River below Lake Blalock near Cowpens, SC, where recurrence interval computations were not appropriate.

  16. Low-flow frequency and flow duration of selected South Carolina streams in the Saluda, Congaree, and Edisto River basins through March 2009

    Feaster, Toby D.; Guimaraes, Wladmir B.


    Part of the mission of the South Carolina Department of Health and Environmental Control and the South Carolina Department of Natural Resources is to protect and preserve South Carolina's water resources. Doing so requires an ongoing understanding of streamflow characteristics of the rivers and streams in South Carolina. A particular need is information concerning the low-flow characteristics of streams, which is especially important for effectively managing the State's water resources during critical flow periods, such as during periods of severe drought like South Carolina has experienced in the last decade or so. The U.S. Geological Survey, in cooperation with the South Carolina Department of Health and Environmental Control, initiated a study in 2008 to update low-flow statistics at continuous-record streamgaging stations operated by the U.S. Geological Survey in South Carolina. This report presents the low-flow statistics for 25 selected streamgaging stations in the Saluda, Congaree, and Edisto River basins in South Carolina, and includes flow durations for the 5-, 10-, 25-, 50-,75-, 90-, and 95-percent exceedances and the annual minimum 1-, 3-, 7-, 14-, 30-, 60-, and 90-day average flows with recurrence intervals of 2, 5, 10, 20, 30, and 50 years, depending on the length of record available at the streamgaging station. The low-flow statistics were computed from records available through March 31, 2009. Of the 25 streamgaging stations for which recurrence interval computations were made, 20 were compared to low-flow statistics that were published in previous U.S. Geological Survey reports. A comparison of the low-flow statistics for the annual minimum 7-day average streamflow with a 10-year recurrence interval (7Q10) from this study with the most recently published values indicates that 18 of the 20 streamgaging stations have values lower than the previous published values. The low-flow statistics are influenced by length of record, hydrologic regime under

  17. Influences of high-flow events on a stream channel altered by construction of a highway bridge: A case study

    Hedrick, Lara B.; Welsh, Stuart A.; Anderson, James T.


    Impacts of highway construction on streams in the central Appalachians are a growing concern as new roads are created to promote tourism and economic development in the area. Alterations to the streambed of a first-order stream, Sauerkraut Run, Hardy County, WV, during construction of a highway overpass included placement and removal of a temporary culvert, straightening and regrading of a section of stream channel, and armourment of a bank with a reinforced gravel berm. We surveyed longitudinal profiles and cross sections in a reference reach and the altered reach of Sauerkraut Run from 2003 through 2007 to measure physical changes in the streambed. During the four-year period, three high-flow events changed the streambed downstream of construction including channel widening and aggradation and then degradation of the streambed. Upstream of construction, at a reinforced gravel berm, bank erosion was documented. The reference section remained relatively unchanged. Knowledge gained by documenting channel changes in response to natural and anthropogenic variables can be useful for managers and engineers involved in highway construction projects.


    Teresa Noga


    Full Text Available Diatoms Bacillariophyceae are a specialized, systematic group of algae, living in different types of ecosystems, and they are very good indicators of water quality. Recently, detailed studies have been carried out in the territory of the Podkarpacie Province on the diversity of diatoms in running waters. The area of study covers mostly the catchment of the biggest rivers of the province (mainly the River Wisłok and cultivated soils. Running waters in the Podkarpacie Province are characterized by a huge species richness of diatoms, 738 different taxa have been found so far. The highest number of taxa was noted in the Wisłok River (400, while the Żołynianka and Różanka streams and the Mleczka were also characterized by huge diversity (from 200 to over 350 taxa. In the majority of studied sites diatoms of alkaline (pH>7 and nutrient rich (eutrophic waters dominated: Navicula lanceolata, N. gregaria, N. capitatoradiata, Nitzschia palea, N. dissipata ssp. dissipata, Achnanthidium minutissimum var. minutissimum, A. pyrenaicum, Amphora pediculus, Diatoma vulgaris, Rhoicosphenia abbreviata, Planothidium lanceolatum, Cocconeis pediculus and C. placentula var. lineata. About 150 taxa were indentified on cultivated soils, among which the largest populations were formed by Hantzschia amphioxys, Mayamaea atomus, Nitzschia palea, N. pusilla, Pinnularia obscura and Stauroneis thermicola.

  19. Model of truly closed circuit of waste stream flow in metallurgical enterprise

    B. Gajdzik


    Full Text Available The publication presents flows of metallurgical waste in manufacturing metallurgical enterprise. On the basis of analysis the structure of waste flows and the way of waste management within the enterprise or outside it were described. In the observation of the metallurgical waste flow a universal model of waste flow structure was created. It may be used in waste management of a metallurgical enterprise with full production cycle (from raw materials processes, through steel production up to final products.

  20. Advances of modeling water flow in variably saturated soils with SWAP

    Dam, van J.C.; Groenendijk, P.; Hendriks, R.F.A.; Kroes, J.G.


    The Soil Water Atmosphere Plant (SWAP) model simulates transport of water, solutes, and heat in the vadose zone in interaction with vegetation development. Special features of the model are generic crop growth, versatile top boundary conditions, macroporous flow, and interaction of soil water with g

  1. Consequences of preferential flow in cracking clay soils for contamination-risk of shallow aquifers

    Oostindie, K.; Bronswijk, J.J.B.


    A method is presented to asses the contamination risk of aquifers covered with cracking clay soils, with special emphasis on preferential flow through shrinkage cracks. A water extraction area was divided into units with homogeneous soil types and hydrological conditions. For each unit, a one-dimens

  2. Advances of modeling water flow in variably saturated soils with SWAP

    Dam, van J.C.; Groenendijk, P.; Hendriks, R.F.A.; Kroes, J.G.


    The Soil Water Atmosphere Plant (SWAP) model simulates transport of water, solutes, and heat in the vadose zone in interaction with vegetation development. Special features of the model are generic crop growth, versatile top boundary conditions, macroporous flow, and interaction of soil water with


    O. N. Prokof'ev


    Full Text Available The purpose of work is to estimate the possible decreasing of the density of  137 Cs sediment in the soil influenced by the horizontal flowing basing on the analysis of on location observations on the density of  137 Cs sediment in the soil after the Chernobyl accident.

  4. Field tracer investigation of unsaturated zone flow paths and mechanisms in agricultural soils of northwestern Mississippi, USA

    Perkins, K.S.; Nimmo, J.R.; Rose, C.E.; Coupe, R.H.


    In many farmed areas, intensive application of agricultural chemicals and withdrawal of groundwater for irrigation have led to water quality and supply issues. Unsaturated-zone processes, including preferential flow, play a major role in these effects but are not well understood. In the Bogue Phalia basin, an intensely agricultural area in the Delta region of northwestern Mississippi, the fine-textured soils often exhibit surface ponding and runoff after irrigation and rainfall as well as extensive surface cracking during prolonged dry periods. Fields are typically land-formed to promote surface flow into drainage ditches and streams that feed into larger river ecosystems. Downward flow of water below the root zone is considered minimal; regional groundwater models predict only 5% or less of precipitation recharges the heavily used alluvial aquifer. In this study transport mechanisms within and below the root zone of a fallow soybean field were assessed by performing a 2-m ring infiltration test with tracers and subsurface monitoring instruments. Seven months after tracer application, 48 continuous cores were collected for tracer extraction to define the extent of water movement and quantify preferential flow using a mass-balance approach. Vertical water movement was rapid below the pond indicating the importance of vertical preferential flow paths in the shallow unsaturated zone, especially to depths where agricultural disturbance occurs. Lateral flow of water at shallow depths was extensive and spatially non-uniform, reaching up to 10. m from the pond within 2. months. Within 1. month, the wetting front reached a textural boundary at 4-5. m between the fine-textured soil and sandy alluvium, now a potential capillary barrier which, prior to extensive irrigation withdrawals, was below the water table. Within 10. weeks, tracer was detectable at the water table which is presently about 12. m below land surface. Results indicate that 43% of percolation may be through

  5. Low-flow frequency and flow-duration characteristics of selected streams in Alabama through March 2014

    Feaster, Toby D.; Lee, Kathyrn G.


    Low-flow statistics are needed by water-resource engineers, planners, and managers to protect and manage the water resources of Alabama. The accuracy of these statistics is influenced by such factors as length of record and specific hydrologic conditions measured in those records. As such, it is generally recommended that flow statistics be updated about every 10 years to provide improved and representative low-flow characteristics. The previous investigation of low-flow characteristics for Alabama included data through September 1990. Since that time, Alabama has experienced several historic droughts highlighting the need to update the low-flow characteristics at U.S. Geological Survey streamgaging stations. Consequently, this investigation was undertaken in cooperation with a number of State and local agencies to update low-flow frequency and flow-duration statistics at 210 continuous-record streamgaging stations in Alabama and 67 stations from basins that are shared with surrounding States. The flow characteristics were computed on the basis of available data through March 2014.

  6. A Numerical Method for Computing the Transonic Fan Duct Flow over a Centerbody into an Exterior Free Stream - Program Tea-343,


    to Boundaries 8. Application of the Prescribed Inlet Flow Condition 27 to the Difference Equation 9. Application of the Boundary Conditions for the 30...formula for the hyperbolic case analogous to Eq. (46) for the outside stream may easily be written down. 8. Application of the Prescribed Inlet Flow Condition to

  7. Channel geometry change of a first-order stream after a small debris flow in Ashio Mountains of central Japan

    Hattanji, T.; Wasklewicz, T.


    We examined geometry change of a steep first-order channel with a laserscanner before and after a small debris flow. The study site is located in chert area, Ashio Mountains, Japan. On August 12, 2005, a 20-year storm event with maximum 1-hour rainfall of 75.4 mm/h triggered a small landslide at a steep channel head. The sliding material moved as a debris flow along the first-order channel (C3) to the mouth. We successfully measured high-resolution channel topography with the Leica Geosystems High-Definition Surveying Laser Scanner before (April 30) and after the debris-flow event (October 9-11). Width, depth and other related parameters were measured for 30 selected cross sections. Bankfull stage of this first-order channel after the debris-flow event is much higher than two-year flood stage. The magnitude of channel geometry change varies non-linearly in downstream direction. The non-linear variability is attributed to differences in stream bed and bank characteristics. Bedrock-channel reach is less impacted by the debris flow. The largest magnitude changes in the channel geometry parameters occur along colluvially confined channel reaches.

  8. Instability of the roll/streak structure induced by free-stream turbulence in pre-transitional Couette flow

    Farrell, Brian F; Nikolaidis, Marios-Andreas


    Although the roll/streak structure is ubiquitous in pre-transitional wall-bounded shear flow, this structure is linearly stable if the idealization of laminar flow is made. Lacking an instability, the large transient growth of the roll/streak structure has been invoked to explain its appearance as resulting from chance occurrence in the free-stream turbulence (FST) of perturbations configured to optimally excite it. However, there is an alternative interpretation which is that FST interacts with the roll/streak structure to destabilize it. Statistical state dynamics (SSD) provides analysis methods for studying instabilities of this type which arise from interaction between the coherent and incoherent components of turbulence. Stochastic structural stability theory (S3T), which implements SSD in the form of a closure at second order, is used to analyze the SSD modes arising from interaction between the coherent streamwise invariant component and the incoherent FST component of turbulence. The least stable S3T ...

  9. Low-flow frequency and flow duration of selected South Carolina streams in the Pee Dee River basin through March 2007

    Feaster, Toby D.; Guimaraes, Wladmir B.


    Part of the mission of the South Carolina Department of Health and Environmental Control and the South Carolina Department of Natural Resources is to protect and preserve South Carolina's water resources. Doing so requires an ongoing understanding of streamflow characteristics of the rivers and streams in South Carolina. A particular need is information concerning the low-flow characteristics of streams; this information is especially important for effectively managing the State's water resources during critical flow periods such as the severe drought that occurred between 1998 and 2002 and the most recent drought that occurred between 2006 and 2009. In 2008, the U.S. Geological Survey, in cooperation with the South Carolina Department of Health and Environmental Control, initiated a study to update low-flow statistics at continuous-record streamgaging stations operated by the U.S. Geological Survey in South Carolina. Under this agreement, the low-flow characteristics at continuous-record streamgaging stations will be updated in a systematic manner during the monitoring and assessment of the eight major basins in South Carolina as defined and grouped according to the South Carolina Department of Health and Environmental Control's Watershed Water Quality Management Strategy. Depending on the length of record available at the continuous-record streamgaging stations, low-flow frequency characteristics are estimated for annual minimum 1-, 3-, 7-, 14-, 30-, 60-, and 90-day average flows with recurrence intervals of 2, 5, 10, 20, 30, and 50 years. Low-flow statistics are presented for 18 streamgaging stations in the Pee Dee River basin. In addition, daily flow durations for the 5-, 10-, 25-, 50-, 75-, 90-, and 95-percent probability of exceedance also are presented for the stations. The low-flow characteristics were computed from records available through March 31, 2007. The last systematic update of low-flow characteristics in South Carolina occurred more than 20 years

  10. Andic soil features and debris flows in Italy. New perspective towards prediction

    Scognamiglio, Solange; Calcaterra, Domenico; Iamarino, Michela; Langella, Giuliano; Orefice, Nadia; Vingiani, Simona; Terribile, Fabio


    Debris flows are dangerous hazards causing fatalities and damage. Previous works have demonstrated that the materials involved by debris flows in Campania (southern Italy) are soils classified as Andosols. These soils have peculiar chemical and physical properties which make them fertile but also vulnerable to landslide. In Italy, andic soil properties are found both in volcanic and non-volcanic mountain ecosystems (VME and NVME). Here, we focused on the assessment of the main chemical and physical properties of the soils in the detachment areas of eight debris flows occurred in NVME of Italy in the last 70 years. Such landslides were selected by consulting the official Italian geodatabase (IFFI Project). Andic properties (by means of ammonium oxalate extractable Fe, Si and Al forms for the calculation of Alo+1/2Feo) were also evaluated and a comparison with soils of VME was performed to assess possible common features. Landslide source areas were characterised by slope gradient ranging from 25° to 50° and lithological heterogeneity of the bedrock. The soils showed similar, i.e. all were very deep, had a moderately thick topsoil with a high organic carbon (OC) content decreasing regularly with depth. The cation exchange capacity trend was generally consistent with the OC and the pH varied from extremely to slightly acid, but increased with depth. Furthermore, the soils had high water retention values both at saturation (0.63 to 0.78 cm3 cm-3) and in the dryer part of the water retention curve, and displayed a prevalent loamy texture. Such properties denote the chemical and physical fertility of the investigated ecosystems. The values of Alo+1/2Feoindicated that the soils had vitric or andic features and can be classified as Andosols. The comparison between NVME soils and those of VME showed similar depth, thickness of soil horizons, and family texture, whereas soil pH, degree of development of andic properties and allophane content were higher for VME soils. Such

  11. Temperatures and Heat Flows in a Soil Enclosing a Slinky Horizontal Heat Exchanger

    Pavel Neuberger; Radomír Adamovský; Michaela Šeďová


    Temperature changes and heat flows in soils that host “slinky”-type horizontal heat exchangers are complex, but need to be understood if robust quantification of the thermal energy available to a ground-source heat pump is to be achieved. Of particular interest is the capacity of the thermal energy content of the soil to regenerate when the heat exchangers are not operating. Analysis of specific heat flows and the specific thermal energy regime within the soil, including that captured by the ...

  12. Preferential flow characteristics of reclaimed mine soils in a surface coal mine dump.

    Gang, Lv; Jun, Li; Yexin, Li; Ting, Wang; Yazhuo, Liu; Xinyang, Fu


    There are a large number of macropores/tubular channels of a few centimeters and plant roots in reclaimed dump soils, which are the main reasons for the formation of soil macropores and soil preferential flow. To systematically study the morphological characteristics and variation of soil preferential flow for different reclaimed vegetations in a dump, a dye-staining experiment and physical and chemical analysis were carried out to investigate the formation mechanism and influencing factors of soil preferential flow in the vegetation restoration process. The results indicate that there were differences in the soil water breakthrough curves for different plots. The macropore effluent rate generally increased at first and then tended to stabilize. The soil steady effluent rate decreased with increasing soil depth, which reached the maximum and minimum values at the depths of 0∼5 cm (0.0193∼0.0315 mm s(-1)) and 50∼60 cm (0.0028∼0.0035 mm s(-1)), respectively. Furthermore, the radius of soil macropores under different types of reclaimed vegetation ranged from 0.03 to 4.71 mm, most of which ranged from 0.11 to 2.36 mm. The soil macroporosity of different reclaimed vegetation types ranged from 0.03 to 16.58%, which was significantly greater than 5%. The soil macroporosity determined 65% of the variation in the steady effluent rate and 42% of the variation in the saturated hydraulic conductivity. Furthermore, the dye coverage ratio decreased as the soil layer depth increased in different plots, and there were some differences in each plot. The maximum dye coverage ratio occurred in the 0∼5 cm soil layer, which reached 90.37%. The dye coverage ratio at a depth of 0∼60 cm in six plots followed the order of Robinia pseudoacacia (26.48%) > Ulmus pumila (20.12%) > mixed forest (17.32%) > farmland (15.06%) > shrub (13.97%) > weeds (10.07%). The soil preferential flow mostly occurred in the 0∼40 cm soil depth layer, which occupied more than 93

  13. Hyporheic Exchange Flows and Biogeochemical Patterns near a Meandering Stream: East Fork of the Jemez River, Valles Caldera National Preserve, New Mexico

    Christensen, H.; Wooten, J. P.; Swanson, E.; Senison, J. J.; Myers, K. D.; Befus, K. M.; Warden, J.; Zamora, P. B.; Gomez, J. D.; Wilson, J. L.; Groffman, A.; Rearick, M. S.; Cardenas, M. B.


    A study by the 2012 Hydrogeology Field Methods class of the University of Texas at Austin implemented multiple approaches to evaluate and characterize local hyporheic zone flow and biogeochemical trends in a highly meandering reach of the of the East Fork of the Jemez River, a fourth order stream in northwestern New Mexico. This section of the Jemez River is strongly meandering and exhibits distinct riffle-pool morphology. The high stream sinuosity creates inter-meander hyporheic flow that is also largely influenced by local groundwater gradients. In this study, dozens of piezometers were used to map the water table and flow vectors were then calculated. Surface water and ground water samples were collected and preserved for later geochemical analysis by ICPMS and HPLC, and unstable parameters and alkalinity were measured on-site. Additionally, information was collected from thermal monitoring of the streambed, stream gauging, and from a series of electrical resistivity surveys forming a network across the site. Hyporheic flow paths are suggested by alternating gaining and losing sections of the stream as determined by stream gauging at multiple locations along the reach. Water table maps and calculated fluxes across the sediment-water interface also indicate hyporheic flow paths. We find variability in the distribution of biogeochemical constituents (oxidation-reduction potential, nitrate, ammonium, and phosphate) along interpreted flow paths which is partly consistent with hyporheic exchange. The variability and heterogeneity of reducing and oxidizing conditions is interpreted to be a result of groundwater-surface water interaction. Two-dimensional mapping of biogeochemical parameters show redox transitions along interpreted flow paths. Further analysis of various measured unstable chemical parameters results in observable trends strongly delineated along these preferential flow paths that are consistent with the direction of groundwater flow and the assumed

  14. Hydrodynamic characteristics of overland flow under soil crusts condition%土壤结皮坡面流水动力学特征

    吴秋菊; 吴发启; 王林华


    We investigated the effects of soil crusts on soil erosion mechanism and their relationship, and series of the runoff scouring experiments were conducted in the Soil and Water Conservation Engineering Laboratory in Northwest A&F University. Two soil surface conditions-the crusts surface and the no crusts surface (control) were explored in our studies. The slope of the scouring trough was set up at 10°(17.6%), five flow rates (1.0, 1.4, 2.0, 2.4 and 2.8 L/min) were used to scour the soil. The flow velocity was measured by the staining method. The flow width was measured by a ruler on the top, central and bottom of slope. The water temperature was measured by a thermometer. The sediment discharge rate was collected at the end of the scouring trough. Then the hydrodynamic characteristics of overland flow (the average flow velocity, the average flow depth, the Reynolds number, the shear stress, the stream power and the resistance coefficient) and the relation between hydrodynamic characteristics of overland flow and soil erosion were analyzed. There was a significant effect of soil crusts on hydrodynamic characteristics. The Reynolds number under soil crusts surface was less than 500, which meant the overland flow was laminar flow. The flow velocity was greater on soil crusts surface than that without soil crusts surface, while the flow depth, the shear stress, the stream power and the soil erosion was much lower on soil crusts surface than that without soil crusts surface. The correlation between soil erosion and hydrodynamic characteristics of overland flow was significant (Regression coefficient R>0.90). Soil erosion had a positive linear correlation with Reynolds number and the logarithm of shear stress and stream power, while had a negative liner correlation with resistance coefficient. Therefore, the existence of soil crusts is helpful to reduce soil erosion from the runoff perspective. Due to the importance of the rainfall factor, it is better to study the

  15. Frequency of the debris flow of four selected low-order streams in central Taiwan by using sequential aerial photographs and typhoon rainfall records

    Chang, J.-C.; Shen, S.-M.; Liu, Y.-S.


    The Taiwan Island, located at the collision boundary of the Eurasia Plate and the Philippine Sea Plate, is characterized by intensive weathering, frequent landslides and debris flows. The latter, however, had never been regarded as a serious threat until the extensive debris flows, induced by Typhoon Herb in 1996 and/or Typhoon Toraji in 2001, caused unprecedented hazardous damages in many low-order streams, especially in the Chenyulan river basin, central Taiwan. Certain streams that remained intact in 1996 experienced dramatic change in 2001. For a better understanding of the historical records of the debris flow, a thorough examination of 17~29 versions of aerial photographs (ranging from 1951 to 2000) of four selected small catchments, which are located in the northern part of the Chenyulan basin, were conducted. The result shows that the Fengchiu stream has experienced six debris flow events over last 50 years and stands for the most vulnerable group in the basin. Statistically, the accumulation rainfall amount of an individual typhoon over 200 mm may trigger debris flow in this stream. During the same period, the other three streams did not experience any dramatic change Typhoon Toraji (>400 mm / 12 hrs). The devastating earthquake (magnitude 7.3), which occurred in 1999 and caused extensive landslides and rockfalls, is also believed playing an important role.

  16. New methods for modeling stream temperature using high resolution LiDAR, solar radiation analysis and flow accumulated values to predict stream temperature

    In-stream temperature directly effects a variety of biotic organisms, communities and processes. Changes in stream temperature can render formally suitable habitat unsuitable for aquatic organisms, particularly native cold water species that are not able to adjust. In order to...

  17. Glyphosate and AMPA in U.S. streams, groundwater, precipitation and soils

    Battaglin, William A.; Meyer, Michael T.; Kuivila, Kathryn; Dietze, Julie E.


    Herbicides containing glyphosate are used in more than 130 countries on more than 100 crops. In the United States (U.S.), agricultural use of glyphosate [N-(phosphonomethyl)glycine] has increased from less than 10,000 metric tons per year (active ingredient) in 1993 to more than 70,000 metric tons per year in 2006. In 2006, glyphosate accounted for about 20 percent of all herbicide use (by weight of active ingredient). Glyphosate formulations such as Roundup® are used in homes and in agriculture. Part of the reason for the popularity of glyphosate is the perception that it is an “environmentally benign” herbicide that has low toxicity and little mobility or persistence in the environment. The U.S. Geological Survey developed an analytical method using liquid chromatography/tandem mass spectrometry that can detect small amounts of glyphosate and its primary degradation product aminomethylphosphonic acid (AMPA) in water and sediment. Results from more than 2,000 samples collected from locations distributed across the U.S. indicate that glyphosate is more mobile and occurs more widely in the environment than was previously thought. Glyphosate and AMPA were detected (reporting limits between 0.1 and 0.02 micrograms per liter) in samples collected from surface water, groundwater, rainfall, soil water, and soil, at concentrations from less than 0.1 to more than 100 micrograms per liter. Glyphosate was detected more frequently in rain (86%), ditches and drains (71%), and soil (63%); and less frequently in groundwater (3%) and large rivers (18%). AMPA was detected more frequently in rain (86%), soil (82%), and large rivers (78%); and less frequently in groundwater (8%) and wetlands or vernal pools (37%). Most observed concentrations of glyphosate were well below levels of concern for humans or wildlife, and none exceeded the U.S. Environmental Protection Agency’s Maximum Contaminant Level of 700 micrograms per liter. However, the ecosystem effects of chronic low

  18. Effects of fine root length density and root biomass on soil preferential flow in forest ecosystems

    Yinghu Zhang


    Full Text Available Aim of study: The study was conducted to characterize the impacts of plant roots systems (e.g., root length density and root biomass on soil preferential flow in forest ecosystems. Area of study: The study was carried out in Jiufeng National Forest Park, Beijing, China. Material and methods: The flow patterns were measured by field dye tracing experiments. Different species (Sophora japonica Linn,Platycladus orientalis Franco, Quercus dentata Thunbwere quantified in two replicates, and 12 soil depth were applied. Plant roots were sampled in the sieving methods. Root length density and root biomass were measured by WinRHIZO. Dye coverage was implied in the image analysis, and maximum depth of dye infiltration by direct measurement. Main results: Root length density and root biomass decreased with the increasing distance from soil surface, and root length density was 81.6% higher in preferential pathways than in soil matrix, and 66.7% for root biomass with respect to all experimental plots. Plant roots were densely distributed in the upper soil layers. Dye coverage was almost 100% in the upper 5-10 cm, but then decreased rapidly with soil depth. Root length density and root biomass were different from species: Platycladus orientalis Franco > Quercus dentata Thunb > Sophora japonica Linn. Research highlights: The results indicated that fine roots systems had strong effects on soil preferential flow, particularly root channels enhancing nutrition transport across soil profiles in forest dynamics.


    Huang Guan-hua; Zhang Ren-duo


    Stochastic approaches are useful to quantitatively describe transport behavior over large temporal and spatial scales while accounting for the influence of small-scale variabilities. Numerous solutions have been developed for unsaturated soil water flow based on the lognormal distribution of soil hydraulic conductivity. To our knowledge, no available stochastic solutions for unsaturated flow have been derived on the basis of the normal distribution of hydraulic conductivity. In this paper, stochastic solutions were developed for unsaturated flow by assuming the normal distribution of saturated hydraulic conductivity (Ks). Under the assumption that soil hydraulic properties are second-order stationary, analytical expressions for capillary tension head variance (σ2h) and effective hydraulic conductivity (K*ii) in stratified soils were derived using the perturbation method. The dependence of σ2h and K*ii on soil variability and mean flow variables (the mean capillary tension head and its temporal and spatial gradients) and mean flow conditions (wetting and drying) were systematically analyzed. The calculated variance of capillary tension head with the analytical solution derived in this paper was compared with field experimental data. The good agreement indicates that the analytical solution is applicable to evaluate the variance of capillary tension head of field soils with moderate variability.

  20. Temperatures and Heat Flows in a Soil Enclosing a Slinky Horizontal Heat Exchanger

    Pavel Neuberger


    Full Text Available Temperature changes and heat flows in soils that host “slinky”-type horizontal heat exchangers are complex, but need to be understood if robust quantification of the thermal energy available to a ground-source heat pump is to be achieved. Of particular interest is the capacity of the thermal energy content of the soil to regenerate when the heat exchangers are not operating. Analysis of specific heat flows and the specific thermal energy regime within the soil, including that captured by the heat-exchangers, has been characterised by meticulous measurements. These reveal that high concentrations of antifreeze mix in the heat-transfer fluid of the heat exchanger have an adverse impact on heat flows discharged into the soil.

  1. Water flow and nutrient transport in a layered silt loam soil

    Vos, de J.A.


    Theory, numerical models, and field and laboratory measurements are used to describe and predict water flow and nutrient transport in a layered silt loam soil. One- and two-dimensional models based on the Darcy equation for water flow and the convection-dispersion equation for solute

  2. Aluminum-contaminant transport by surface runoff and bypass flow from an acid sulphate soil

    Minh, L.Q.; Tuong, T.P.; Mensvoort, van M.E.F.; Bouma, J.


    Quantifying the process and the amount of acid-contaminant released to the surroundings is important in assessing the environmental hazards associated with reclaiming acid sulphate soils (ASS). The roles of surface runoff and bypass flow (i.e. the rapid downward flow of free water along macropores t

  3. Sensitivity of the initiation of debris flow to initial soil moisture

    Hu, W.; Xu, Q.; Wang, G. H.; van Asch, T. W J; Hicher, P. Y.


    The initiation of debris flows is commonly attributed either to fluidization as a result of rainfall-induced landslides or to gully erosion induced by concentrated runoffs. A series of flume tests have been performed to show how the initial soil moisture influences the initiation of debris flows. At

  4. Aluminum-contaminant transport by surface runoff and bypass flow from an acid sulphate soil

    Minh, L.Q.; Tuong, T.P.; Mensvoort, van M.E.F.; Bouma, J.


    Quantifying the process and the amount of acid-contaminant released to the surroundings is important in assessing the environmental hazards associated with reclaiming acid sulphate soils (ASS). The roles of surface runoff and bypass flow (i.e. the rapid downward flow of free water along macropores t

  5. Peak flow regression equations For small, ungaged streams in Maine: Comparing map-based to field-based variables

    Lombard, Pamela J.; Hodgkins, Glenn A.


    Regression equations to estimate peak streamflows with 1- to 500-year recurrence intervals (annual exceedance probabilities from 99 to 0.2 percent, respectively) were developed for small, ungaged streams in Maine. Equations presented here are the best available equations for estimating peak flows at ungaged basins in Maine with drainage areas from 0.3 to 12 square miles (mi2). Previously developed equations continue to be the best available equations for estimating peak flows for basin areas greater than 12 mi2. New equations presented here are based on streamflow records at 40 U.S. Geological Survey streamgages with a minimum of 10 years of recorded peak flows between 1963 and 2012. Ordinary least-squares regression techniques were used to determine the best explanatory variables for the regression equations. Traditional map-based explanatory variables were compared to variables requiring field measurements. Two field-based variables—culvert rust lines and bankfull channel widths—either were not commonly found or did not explain enough of the variability in the peak flows to warrant inclusion in the equations. The best explanatory variables were drainage area and percent basin wetlands; values for these variables were determined with a geographic information system. Generalized least-squares regression was used with these two variables to determine the equation coefficients and estimates of accuracy for the final equations.

  6. Experimental analysis of flow of ductile cast iron in stream lined gating systems

    Skov-Hansen, Søren; Green, Nick; Tiedje, Niels Skat


    Streamlined gating systems have been developed for production of high integrity ductile cast iron parts. Flow of ductile cast iron in streamlined gating systems was studied in glass fronted sand moulds where flow in the gating system and casting was recorded by a digital video camera. These resul...

  7. Preliminary report on arsenic and heavy metals contents in soils and stream bed sediments of Cornia, Bruna and Alma coastal plains (Southern Tuscany

    Dughetti F.


    Full Text Available The Department of Earth Sciences of University of Florence has conducted over the past ten years, numerous studies about the distribution of arsenic and heavy metals in mineralized areas of Tuscany, particularly in the Pecora basin. The area hosts several polymetallic ore bodies and a pyrite ore deposit. The studies have identified several geochemical anomalies (As, Cu, Pb, Zn… both in the areas which host the ore bodies and in the coastal plain (Scarlino Plain. To increase the knowledge concerning the distribution of As and heavy metals in other Tuscan coastal plains, research is under way in the alluvial plains of the Bruna, Cornia and Alma rivers. The preliminary analysis have focused on soils and stream sediments, to better understand the correlations between the downstream transport of rivers and the soils. We have made physic-chemical analysis, particle size analysis, mineralogical analysis for X-ray powder diffraction, chemical analysis for the determination of major element (X-ray Fluorescence and for the determination of 35 minor elements and traces (AAS and ICP.Preliminary data show high concentrations of several elements (As, Zn, Co…. The concentrations of these elements in soils and stream bed sediments are not always consistent; in particular we have found higher concentrations in soils than in stream bed sediments in Cornia Plain, while the opposite happens in the Bruna basin. Therefore the natural processes of rocks weathering does not seem to have affected uniformly. The distribution of As and heavy metals in soils and stream bed sediments of the all three basins of interest are still under investigation.

  8. Long-term flow rates and biomat zone hydrology in soil columns receiving septic tank effluent.

    Beal, C D; Gardner, E A; Kirchhof, G; Menzies, N W


    Soil absorption systems (SAS) are used commonly to treat and disperse septic tank effluent (STE). SAS can hydraulically fail as a result of the low permeable biomat zone that develops on the infiltrative surface. The objectives of this experiment were to compare the hydraulic properties of biomats grown in soils of different textures, to investigate the long-term acceptance rates (LTAR) from prolonged application of STE, and to assess if soils were of major importance in determining LTAR. The STE was applied to repacked sand, Oxisol and Vertisol soil columns over a period of 16 months, at equivalent hydraulic loading rates of 50, 35 and 8L/m(2)/d, respectively. Infiltration rates, soil matric potentials, and biomat hydraulic properties were measured either directly from the soil columns or calculated using established soil physics theory. Biomats 1 to 2 cm thick developed in all soils columns with hydraulic resistances of 27 to 39 d. These biomats reduced a 4 order of magnitude variation in saturated hydraulic conductivity (K(s)) between the soils to a one order of magnitude variation in LTAR. A relationship between biomat resistance and organic loading rate was observed in all soils. Saturated hydraulic conductivity influenced the rate and extent of biomat development. However, once the biomat was established, the LTAR was governed by the resistance of the biomat and the sub-biomat soil unsaturated flow regime induced by the biomat. Results show that whilst initial soil K(s) is likely to be important in the establishment of the biomat zone in a trench, LTAR is determined by the biomat resistance and the unsaturated soil hydraulic conductivity, not the K(s) of a soil. The results call into question the commonly used approach of basing the LTAR, and ultimately trench length in SAS, on the initial K(s) of soils.

  9. A synchronized particle image velocimetry and infrared thermography technique applied to an acoustic streaming flow

    Sou, In Mei; Ray, Chittaranjan [University of Hawaii at Manoa, Department of Civil and Environmental Engineering, Honolulu, HI (United States); Allen, John S.; Layman, Christopher N. [University of Hawaii at Manoa, Department of Mechanical Engineering, Honolulu, HI (United States)


    Subsurface coherent structures and surface temperatures are investigated using simultaneous measurements of particle image velocimetry (PIV) and infrared (IR) thermography. Results for coherent structures from acoustic streaming and associated heating transfer in a rectangular tank with an acoustic horn mounted horizontally at the sidewall are presented. An observed vortex pair develops and propagates in the direction along the centerline of the horn. From the PIV velocity field data, distinct kinematic regions are found with the Lagrangian coherent structure (LCS) method. The implications of this analysis with respect to heat transfer and related sonochemical applications are discussed. (orig.)

  10. Carcinogenic ptaquiloside in stream water at base flow and during storm events

    Strobel, Bjarne W.; Clauson-Kaas, Frederik; Hansen, Hans Chr. Bruun


    The globally occurring bracken fern (Pteridium sp.) is widespread in the broadleaf forests of Denmark, and densely populates several vegetation types in the Americas, Australia and on the British Isles. Bracken is toxic to livestock when consumed, and a group of potent carcinogens have been...... are crucial to measure these 1-2 hours pulses of natural toxins in the stream. Collected canopy through fall showed high amounts of PTA (up to 169 µg/L) leached from bracken fronds during rainfall, with no apparent deterioration of this source throughout the storm event. The results are important...

  11. Impact of climate change on the stream flow of the lower Brahmaputra: trends in high and low flows based on discharge-weighted ensemble modelling

    A. K. Gain


    Full Text Available Climate change is likely to have significant effects on the hydrology. The Ganges-Brahmaputra river basin is one of the most vulnerable areas in the world as it is subject to the combined effects of glacier melt, extreme monsoon rainfall and sea level rise. To what extent climate change will impact river flow in the Brahmaputra basin is yet unclear, as climate model studies show ambiguous results. In this study we investigate the effect of climate change on both low and high flows of the lower Brahmaputra. We apply a novel method of discharge-weighted ensemble modeling using model outputs from a global hydrological models forced with 12 different global climate models (GCMs. Our analysis shows that only a limited number of GCMs are required to reconstruct observed discharge. Based on the GCM outputs and long-term records of observed flow at Bahadurabad station, our method results in a multi-model weighted ensemble of transient stream flow for the period 1961–2100. Using the constructed transients, we subsequently project future trends in low and high river flow. The analysis shows that extreme low flow conditions are likely to occur less frequent in the future. However a very strong increase in peak flows is projected, which may, in combination with projected sea level change, have devastating effects for Bangladesh. The methods presented in this study are more widely applicable, in that existing multi-model streamflow simulations from global hydrological models can be weighted against observed streamflow data to assess at first order the effects of climate change for specific river basins.

  12. A Coupling Simulation Between Soil Scour and Seepage Flow by Using a Stabilized ISPH Method

    Nogami Tomotaka


    Full Text Available In 2011, the example that breakwaters collapsed because of the basic ground’s destabilization was reported by Tohoku-Kanto earthquake tsunami. Fluid-Structure-Soil coupling simulation is desired for a systematic comprehension of the breakwater collapse mechanism, and it may help to develop next disaster prevention method. In this study, A particle simulation tool based on the SPH has been modified and improved to analyze seepage flow and soil scouring. In seepage flow analysis, as a first step, this simulation treat the surface flow and seepage flow interactions by using governing equation. In the scouring analysis, soil scour is judged by an empirical criteria based on quicksand quantity formula.

  13. An Active Region Model for Capturing Fractal Flow Patterns inUnsaturated Soils: Model Development

    Liu, Hui-Hai; Zhang, R.; Bodvarsson, Gudmundur S.


    Preferential flow commonly observed in unsaturated soils allows rapid movement of solute from the soil surface or vadose zone to the groundwater, bypassing a significant volume of unsaturated soil and increasing the risk of groundwater contamination. A variety of evidence indicates that complex preferential patterns observed from fields are fractals. In this study, we developed a relatively simple active region model to incorporate the fractal flow pattern into the continuum approach. In the model, the flow domain is divided into active and inactive regions. Flow occurs preferentially in the active region (characterized by fractals), and inactive region is simply bypassed. A new constitutive relationship (the portion of the active region as a function of saturation) was derived. The validity of the proposed model is demonstrated by the consistency between field observations and the new constitutive relationship.

  14. sedFlow – a tool for simulating fractional bedload transport and longitudinal profile evolution in mountain streams

    F. U. M. Heimann


    floods. The model is intended for temporal scales from the individual event (several hours to few days up to longer-term evolution of stream channels (several years. The envisaged spatial scale covers complete catchments at a spatial discretisation of several tens of metres to a few hundreds of metres. sedFlow can deal with the effects of streambeds that slope uphill in a downstream direction and uses recently proposed and tested approaches for quantifying macro-roughness effects in steep channels. sedFlow offers different options for bedload transport equations, flow-resistance relationships and other elements which can be selected to fit the current application in a particular catchment. Local grain-size distributions are dynamically adjusted according to the transport dynamics of each grain-size fraction. sedFlow features fast calculations and straightforward pre- and postprocessing of simulation data. The high simulation speed allows for simulations of several years, which can be used, e.g., to assess the long-term impact of river engineering works or climate change effects. In combination with the straightforward pre- and postprocessing, the fast calculations facilitate efficient workflows for the simulation of individual flood events, because the modeller gets the immediate results as direct feedback to the selected parameter inputs. The model is provided together with its complete source code free of charge under the terms of the GNU General Public License (GPL ( Examples of the application of sedFlow are given in a companion article by Heimann et al. (2015.

  15. Asymmetric flow field-flow fractionation of manufactured silver nanoparticles spiked into soil solution

    Koopmans, G.F.; Hiemstra, T.; Regelink, I.C.; Molleman, B.; Comans, R.N.J.


    Manufactured metallic silver nanoparticles (AgNP) are intensively utilized in consumer products and this will inevitably lead to their release to soils. To assess the environmental risks of AgNP in soils, quantification of both their concentration and size in soil solution is essential. We developed

  16. Collaborative Approaches to Flow Restoration in Intermittent Salmon-Bearing Streams: Salmon Creek, CA, USA

    Cleo Woelfle-Erskine


    Full Text Available In Mediterranean-climate regions of California and southern Oregon, juvenile salmon depend on groundwater aquifers to sustain their tributary habitats through the dry summers. Along California’s North Coast streams, private property regimes on land have created commons tragedies in groundwater and salmon fisheries, both classic examples of commons that are often governed collectively and sustainably by their users. Understanding the linkages between salmon and groundwater is one major focus of salmon recovery and climate change adaptation planning in central California and increasingly throughout the Pacific Northwest. In this paper, I use extended field interviews and participant-observation in field ecology campaigns and regulatory forums to explore how, in one water-scarce, salmon-bearing watershed on California’s central coast, collaborators are synthesizing agency and landowner data on groundwater and salmon management. I focus on three projects undertaken by citizen scientists in collaboration with me and Gold Ridge Resource Conservation District staff: salmonid censuses, mapping of wet and dry stream reaches and well monitoring. I find that collaborative research initiated by local residents and agency personnel has, in some cases, created a new sense of ecological possibility in the region. I also consider some limitations of this collaborations, namely the lack of engagement with indigenous Pomo and Miwok tribal members, with the Confederated Tribes of Graton Rancheria and with farmworkers and other marginalized residents, and suggest strategies for deepening environmental justice commitments in future collaborative work.

  17. Grass Cover Influences Hydrophysical Parameters and Heterogeneity of Water Flow in a Sandy Soil



    Vegetation cover has a major effect on water flow in soils.Two sites,separated by distance of about 50 m,were selected to quantify the influence of grass cover on hydrophysical parameters and heterogeneity of water flow in a sandy soil emerging during a heavy rain following a long hot,dry period.A control soil (pure sand) with limited impact of vegetation or organic matter was obtained by sampling at 50 cm depth beneath a glade area,and a grassland soil was covered in a 10 cm thick humic layer and colonised by grasses.The persistence of water repellency was measured using the water drop penetration time test,sorptivity and unsaturated hydraulic conductivity using a mini disk infiltrometer,and saturated hydraulic conductivity using a double-ring infiltrometer.Dye tracer experiments were used to assess the heterogeneity of water flow,and both the modified method for estimating effective cross section and an original method for assessing the degree of preferential flow were used to quantify this heterogeneity from the images of dyed soil profiles.Most hydrophysical parameters were substantially different between the two surfaces.The grassland soil had an index of water repellency about 10 times that of pure sand and the persistence of water repellency almost 350 times that of pure sand.Water and ethanol sorptivities in the grassland soil were 7% and 43%,respectively,of those of the pure sand.Hydraulic conductivity and saturated hydraulic conductivities in the grassland soil were 5% and 16% of those of the pure sand,respectively.Dye tracer experiments revealed a stable flow with "air-draining" condition in pure sand and well-developed preferential flow in grassland soil,corresponding to individual grass tussocks and small micro-depressions.The grassland soil was substantially more water repellent and had 3 times the degree of preferential flow compared to pure sand.The results of this study reinforce our view that the consequences of any change in climate

  18. Flow pathways of bromide and Brilliant Blue FCF tracers in caliche soils

    Nobles, M. M.; Wilding, L. P.; Lin, H. S.


    Land use of caliche soils in limestone regions of Texas is increasingly shifting from traditional ranchland to residential and industrial development. However, little information is available on water flow and solute transport through soils of these landscapes, or their potential suitability for wastewater disposal and bioremediation. This study determined the impacts of landscape position on soil hydrologic functions by using Brilliant Blue FCF and Br - tracers to characterize flow pathways through soils of stepped terrains. Aqueous tracer solution was applied to surface (and in some cases subsurface) horizons of selected riser, tread, floodplain, and upland summit sites. Brilliant Blue FCF and Br - pathways were analyzed based on vertical sections excavated through each application site. While Brilliant Blue FCF demonstrated preferential flow along macropores, Br - moved through soil matrix primarily in piston flow pattern. In most cases, Br - was less retarded and moved to greater vertical and horizontal distances than Brilliant Blue FCF. Cemented Bk, Bkm, C, Cr, Crk, and R horizons acted as aquitards, resulting in considerable horizontal transport of both tracers beyond the direct infiltration zone. Significant volumes of limestone rock clasts, together with soil, were involved in solute transport and thus contributed to the soil's ability to serve as bioremediation and moisture storage media. High limestone gravel content and rapid solute transport through subsurface horizons to aquitards in deep riser soils indicate that they may serve as hydrological recharge sites with potential for ephemeral water tables, increased water storage and greater bioremediation potential. Shallow tread sites may be capable of producing seasonal saturation above restrictive horizons and increased surface runoff, becoming local hydrological discharge sites. This could conceivably lead to surface water contamination; however, these locales are hydrologically buffered by recharge

  19. Ensemble kalman filtering to perform data assimilation with soil water content probes and pedotransfer functions in modeling water flow in variably saturated soils

    Data from modern soil water contents probes can be used for data assimilation in soil water flow modeling, i.e. continual correction of the flow model performance based on observations. The ensemble Kalman filter appears to be an appropriate method for that. The method requires estimates of the unce...

  20. Development of a stream-aquifer numerical flow model to assess river water management under water scarcity in a Mediterranean basin.

    Mas-Pla, Josep; Font, Eva; Astui, Oihane; Menció, Anna; Rodríguez-Florit, Agustí; Folch, Albert; Brusi, David; Pérez-Paricio, Alfredo


    Stream flow, as a part of a basin hydrological cycle, will be sensible to water scarcity as a result of climate change. Stream vulnerability should then be evaluated as a key component of the basin water budget. Numerical flow modeling has been applied to an alluvial formation in a small mountain basin to evaluate the stream-aquifer relationship under these future scenarios. The Arbúcies River basin (116 km(2)) is located in the Catalan Inner Basins (NE Spain) and its lower reach, which is related to an alluvial aquifer, usually becomes dry during the summer period. This study seeks to determine the origin of such discharge losses whether from natural stream leakage and/or induced capture due to groundwater withdrawal. Our goal is also investigating how discharge variations from the basin headwaters, representing potential effects of climate change, may affect stream flow, aquifer recharge, and finally environmental preservation and human supply. A numerical flow model of the alluvial aquifer, based on MODFLOW and especially in the STREAM routine, reproduced the flow system after the usual calibration. Results indicate that, in the average, stream flow provides more than 50% of the water inputs to the alluvial aquifer, being responsible for the amount of stored water resources and for satisfying groundwater exploitation for human needs. Detailed simulations using daily time-steps permit setting threshold values for the stream flow entering at the beginning of the studied area so surface discharge is maintained along the whole watercourse and ecological flow requirements are satisfied as well. The effects of predicted rainfall and temperature variations on the Arbúcies River alluvial aquifer water balance are also discussed from the outcomes of the simulations. Finally, model results indicate the relevance of headwater discharge management under future climate scenarios to preserve downstream hydrological processes. They also point out that small mountain basins

  1. Manual for estimating selected streamflow characteristics of natural-flow streams in the Colorado River basin in Utah

    Christensen, R.C.; Johnson, E.B.; Plantz, G.G.


    Methods are presented for estimating 10 streamflow characteristics at three types of sites on natural flow streams in the Colorado River Basin in Utah. The streamflow characteristics include average discharge and annual maximum 1-, 7-, and 15-day mean discharges for recurrence intervals of 10, 50 and 100 years. At or near gaged sites, two methods weight gaging station data with regression equation values to estimate streamflow characteristics. At sites on ungaged streams, a method estimates streamflow characteristics using regression equations. The regression equations relate the streamflow characteristics to the following basin and climatic characteristics: contributing drainage area, mean basin elevation, mean annual precipitation, main channel slope, and forested area. Separate regression equations were developed for four hydrologically distinct regions in the study area. The standard error of estimate for the 10 streamflow characteristics ranges from 13% to 87%. Basin, climatic, and streamflow characteristics, available as of September 30, 1981, are presented for 135 gaging stations in Utah, Arizona, Colorado, and Wyoming. In addition, weighted estimates of the streamflow characteristics based on station data and the regression equation estimates are provided for most gaging stations. (Author 's abstract)

  2. Estimate of heavy metals in soil and streams using combined geochemistry and field spectroscopy in Wan-sheng mining area, Chongqing, China

    Song, Lian; Jian, Ji; Tan, De-Jun; Xie, Hong-Bing; Luo, Zhen-Fu; Gao, Bo


    Heavy metals contaminated soils and water will become a major environmental issue in the mining areas. This paper intends to use field hyper-spectra to estimate the heavy metals in the soil and water in Wan-sheng mining area in Chongqing. With analyzing the spectra of soil and water, the spectral features deriving from the spectral of the soils and water can be found to build the models between these features and the contents of Al, Cu and Cr in the soil and water by using the Stepwise Multiple Linear Regression (SMLR). The spectral features of Al are: 480 nm, 500 nm, 565 nm, 610 nm, 680 nm, 750 nm, 1000 nm, 1430 nm, 1755 nm, 1887 nm, 1920 nm, 1950 nm, 2210 nm, 2260 nm; The spectral features of Cu are: 480 nm, 500 nm, 610 nm, 750 nm, 860 nm, 1300 nm, 1430 nm, 1920 nm, 2150 nm, 2260 nm; And the spectral features of Cr are: 480 nm, 500 nm, 610 nm, 715 nm, 750 nm, 860 nm, 1300 nm, 1430 nm, 1755 nm, 1920 nm, 1950 nm. With these features, the best models to estimate the heavy metals in the study area were built according to the maximal R2. The R2 of the models of estimating Al, Cu and Cr in the soil and water are 0.813, 0.638, 0.604 and 0.742, 0.584, 0.513 respectively. And the gradient maps of these three types of heavy metals' concentrations can be created by using the Inverse distance weighted (IDW).The gradient maps indicate that the heavy metals in the soil have similar patterns, but in the North-west of the streams in the study area, the contents are of great differences. These results show that it is feasible to predict contaminated heavy metals in the soils and streams due to mining activities by using the rapid and cost-effective field spectroscopy.

  3. Robust, low-cost data loggers for stream temperature, flow intermittency, and relative conductivity monitoring

    Chapin, Thomas; Todd, Andrew S.; Zeigler, Matthew P.


    Water temperature and streamflow intermittency are critical parameters influencing aquatic ecosystem health. Low-cost temperature loggers have made continuous water temperature monitoring relatively simple but determining streamflow timing and intermittency using temperature data alone requires significant and subjective data interpretation. Electrical resistance (ER) sensors have recently been developed to overcome the major limitations of temperature-based methods for the assessment of streamflow intermittency. This technical note introduces the STIC (Stream Temperature, Intermittency, and Conductivity logger); a robust, low-cost, simple to build instrument that provides long-duration, high-resolution monitoring of both relative conductivity (RC) and temperature. Simultaneously collected temperature and RC data provide unambiguous water temperature and streamflow intermittency information that is crucial for monitoring aquatic ecosystem health and assessing regulatory compliance. With proper calibration, the STIC relative conductivity data can be used to monitor specific conductivity.

  4. Irrigant flow during photon-induced photoacoustic streaming (PIPS) using Particle Image Velocimetry (PIV).

    Koch, Jon D; Jaramillo, David E; DiVito, Enrico; Peters, Ove A


    This study aimed to compare fluid movements generated from photon-induced photoacoustic streaming (PIPS) and passive ultrasonic irrigation (PUI). Particle Image Velocimetry (PIV) was performed using 6-μm melamine spheres in water. Measurement areas were 3-mm-long sections of the canal in the coronal, midroot and apical regions for PIPS (erbium/yttrium-aluminium garnet (Er:YAG) laser set at 15 Hz with 20 mJ), or passive ultrasonic irrigation (PUI, non-cutting insert at 30% unit power) was performed in simulated root canals prepared to an apical size #30/0.04 taper. Fluid movement was analysed directly subjacent to the apical ends of ultrasonic insert or fiber optic tips as well as at midroot and apically. During PUI, measured average velocities were around 0.03 m/s in the immediate vicinity of the sides and tip of the ultrasonic file. Speeds decayed to non-measureable values at a distance of about 2 mm from the sides and tip. During PIPS, typical average speeds were about ten times higher than those measured for PUI, and they were measured throughout the length of the canal, at distances up to 20 mm away. PIPS caused higher average fluid speeds when compared to PUI, both close and distant from the instrument. The findings of this study could be relevant to the debriding and disinfecting stage of endodontic therapy. Irrigation enhancement beyond needle irrigation is relevant to more effectively eradicate microorganisms from root canal systems. PIPS may be an alternative approach due to its ability to create high streaming velocities further away from the activation source compared to ultrasonic activation.

  5. Daily Runoff Simulation at River Network by the WWASS (Watershed Water balance And Stream flow Simulation) Model

    Kim, Hyun Young; Hwang, Cheol Sang; Kang, Seok Man; Lee, Kwang Ya [Rural Development Corp., Seoul (Korea)


    When various elements of water balance are displayed at several points of a river network, the runoff amounts at an estuary especially tidal influenced are affected from the elements. This problem can be solved by a model that can generalize and formulate the elements and simulate daily runoff and water requirement. The WWASS model was built using DIROM for the simulation of daily runoff and water requirement, and the water balance elements were modeled to be balanced at the each control point of river network. The model was calibrated, verified and applied to the watershed for the Saemankeum tidal land reclamation development project. It showed that the results from the stream flow simulation at the Mankyung and Dongjin estuary were acceptable for the design of the Saemankeum estuary reservoir. (author). 7 refs., 3 tabs., 8 figs.

  6. Hydrography - Streams and Shorelines

    California Department of Resources — The hydrography layer consists of flowing waters (rivers and streams), standing waters (lakes and ponds), and wetlands -- both natural and manmade. Two separate...

  7. Determination of the Effect of Water Depth and Flow Velocity on the Quality of an In-Stream Habitat in Terms of Climate Change

    V. Macura


    Full Text Available The study is focused on the objectification of an assessment of the quality of an in-stream habitat in mountain and piedmont streams by the decision-making Instream Flow Incremental Methodology (IFIM due to climate change. The quality of the habitat was assessed on the basis of a bioindication, represented by ichthyofauna. Sixty-four reaches of 47 watercourses in five river basins in Slovakia, in which ichthyologic, topographic, and hydraulic measurements were performed, were evaluated. The effect of the physical characteristics of the stream channel on the quality of the in-stream habitat has been verified on a number of reference reaches in which the measurements were performed at different water levels. From the set of the data measured, an analysis aimed at determining the impact of individual characteristics on the quality of an in-stream habitat has been carried out. The results show the optimum ratio of the weights of the flow velocity and water depth for an assessment of the quality of an in-stream habitat due to climate change.

  8. Detailed predictions of climate induced changes in the thermal and flow regimes in mountain streams of the Iberian Peninsula

    Santiago, José M.; Muñoz-Mas, Rafael; García de Jalón, Diego; Solana, Joaquín; Alonso, Carlos; Martínez-Capel, Francisco; Ribalaygua, Jaime; Pórtoles, Javier; Monjo, Robert


    Streamflow and temperature regimes are well-known to influence on the availability of suitable physical habitat for instream biological communities. General Circulation Models (GCMs) have predicted significant changes in timing and geographic distribution of precipitation and atmospheric temperature for the ongoing century. However, differences in these predictions may arise when focusing on different spatial and temporal scales. Therefore, to perform substantiated mitigation and management actions detailed scales are necessary to adequately forecast the consequent thermal and flow regimes. Regional predictions are relatively abundant but detailed ones, both spatially and temporally, are still scarce. The present study aimed at predicting the effects of climate change on the thermal and flow regime in the Iberian Peninsula, refining the resolution of previous studies. For this purpose, the study encompassed 28 sites at eight different mountain rivers and streams in the central part of the Iberian Peninsula (Spain). The daily flow was modelled using different daily, monthly and quarterly lags of the historical precipitation and temperature time series. These precipitation-runoff models were developed by means of M5 model trees. On the other hand water temperature was modelled at similar time scale by means of nonlinear regression from dedicated site-specific data. The developed models were used to simulate the temperature and flow regime under two Representative Concentration Pathway (RCPs) climate change scenarios (RCP 4.5 and RCP 8.5) until the end of the present century by considering nine different GCMs, which were pertinently downscaled. The precipitation-runoff models achieved high accuracy (NSE>0.7), especially in regards of the low flows of the historical series. Results concomitantly forecasted flow reductions between 7 and 17 % (RCP4.5) and between 8 and 49% (RCP8.5) of the annual average in the most cases, being variable the magnitude and timing at each

  9. Water flow in soil from organic dairy rotations

    Lamandé, Mathieu; Eriksen, Jørgen; Krogh, Paul Henning


    and fertilizer practice on the movement of water through sandy loam soil profiles were investigated in managed grassland of a dairy operation. Experiments using tracer chemicals were performed, with or without cattle slurry application, with cutting or grazing, in the 1st and the 3rd year of ley, and in winter...

  10. Investigation of Relationship Between Hydrologic Processes of Precipitation, Evaporation and Stream Flow Using Linear Time Series Models (Case study: Western Basins of Lake Urmia

    M. Moravej


    Full Text Available Introduction: Studying the hydrological cycle, especially in large scales such as water catchments, is difficult and complicated despite the fact that the numbers of hydrological components are limited. This complexity rises from complex interactions between hydrological components and environment. Recognition, determination and modeling of all interactive processes are needed to address this issue, but it's not feasible for dealing with practical engineering problems. So, it is more convenient to consider hydrological components as stochastic phenomenon, and use stochastic models for modeling them. Stochastic simulation of time series models related to water resources, particularly hydrologic time series, have been widely used in recent decades in order to solve issues pertaining planning and management of water resource systems. In this study time series models fitted to the precipitation, evaporation and stream flow series separately and the relationships between stream flow and precipitation processes are investigated. In fact, the three mentioned processes should be modeled in parallel to each other in order to acquire a comprehensive vision of hydrological conditions in the region. Moreover, the relationship between the hydrologic processes has been mostly studied with respect to their trends. It is desirable to investigate the relationship between trends of hydrological processes and climate change, while the relationship of the models has not been taken into consideration. The main objective of this study is to investigate the relationship between hydrological processes and their effects on each other and the selected models. Material and Method: In the current study, the four sub-basins of Lake Urmia Basin namely Zolachay (A, Nazloochay (B, Shahrchay (C and Barandoozchay (D were considered. Precipitation, evaporation and stream flow time series were modeled by linear time series. Fundamental assumptions of time series analysis namely

  11. Sediments and processes on a small stream-flow dominated, devonian alluvial fan, Shetland Islands

    Allen, Philip A.


    The main conglomerate type of a small Devonian alluvial fan in Shetland, northern Britain, is an inverse to normally graded framework-supported gravel. The sedimentological details of these beds and fundamental considerations of the mechanics of movement of highly concentrated flows suggests that neither debris-flow nor grain-flow were responsible for the deposition of these conglomerates. On the contrary, these inverse to normally graded conglomerates were deposited by water as thick gravel sheets with little topographic relief, but broadly analogous to longitudinal bars. They were deposited under high aggradation conditions first on the rising and then on the falling flood. The high concentration of material in transport on the rising and peak flood was responsible for the polymodal and unstratified nature of the conglomerates. As the flood waned, normal grading was developed and a preferred horizontal fabric was produced under low concentrations of sediment. Other conglomerate types, comparatively of lesser importance, were deposited from highly concentrated clast dispersions and are notably richer in matrix and locally possess inverse grading. The hydrological environment was one of flashy discharges of short duration but of high velocity. Flow was dissipated rapidly, perhaps due to extreme water loss. This example from the Devonian of Shetland provides an interesting alternative to the mass-transport dominated fan models currently in vogue.

  12. Synthesis of a parallel data stream processor from data flow process networks

    Zissulescu-Ianculescu, Claudiu


    In this talk, we address the problem of synthesizing Process Network specifications to FPGA execution platforms. The process networks we consider are special cases of Kahn Process Networks. We call them COMPAAN Data Flow Process Networks (CDFPN) because they are provided by a translator called the C

  13. Preferential flow effects on transport and fate of chemicals and microorganisms in soils irrigated with wastewater

    Puddu, Rita; Corrias, Roberto; Dessena, Maria Antonietta; Ferralis, Marcella; Marras, Gabriele; Pin, Paola; Spanu, Paola


    This work is part of a multidisciplinary research properly planned by the ENAS (Cagliari-Sardinia-Italy) to verify the consequences of urban wastewater reuse in irrigation practices on chemical, biological and hydrological behavior of agricultural soils of the Had as Soualem area (Morocco). The area consists of Fluventic Haploxerept soils, according to USDA Soil Taxonomy. Undisturbed large soil columns, 70 cm height and 20 cm diameter, were collected from plots, the locations of which were preliminarily individuated through a prior pedological study. The soils are characterized by an apparent structure, suggesting that preferential flow processes may occur in the study area, which may impact usable groundwater at depth. Wastewater reuse for irrigation simultaneously solves water shortage and wastewater disposal problems. Unfortunately, wastewaters generally contain high concentrations of suspended and dissolved solids, both organic and inorganic, and microbial contaminants (virus and bacteria) added to wastewater during domestic and industrial usage. Most of these contaminants are only partially removed during conventional sewage treatment so they remain in the irrigation water. Although adsorbing ions and microbes are relatively immobile within porous media, preferential flow and adsorption to mobile colloids can enhance their transport. There is limited knowledge regarding the role of preferential flow and colloidal transport on adsorbing contaminants. The main aim of this research is to determine the influence of preferential flow and colloids on wastewater contaminant transport. Leaching rates and arrival time of wastewater contaminants will be determined using field and laboratory measurements at the study sites in combination with preferential flow numerical modeling. To achieve these objectives the soil columns were analyzed for physical, chemical, and microbial characterization. At the laboratory, an experimental facility was set up and sensors for

  14. Modeled intermittency risk for small streams in the Upper Colorado River Basin under climate change

    Reynolds, Lindsay V.; Shafroth, Patrick B.; Poff, N. LeRoy


    Longer, drier summers projected for arid and semi-arid regions of western North America under climate change are likely to have enormous consequences for water resources and river-dependent ecosystems. Many climate change scenarios for this region involve decreases in mean annual streamflow, late summer precipitation and late-summer streamflow in the coming decades. Intermittent streams are already common in this region, and it is likely that minimum flows will decrease and some perennial streams will shift to intermittent flow under climate-driven changes in timing and magnitude of precipitation and runoff, combined with increases in temperature. To understand current intermittency among streams and analyze the potential for streams to shift from perennial to intermittent under a warmer climate, we analyzed historic flow records from streams in the Upper Colorado River Basin (UCRB). Approximately two-thirds of 115 gaged stream reaches included in our analysis are currently perennial and the rest have some degree of intermittency. Dry years with combinations of high temperatures and low precipitation were associated with more zero-flow days. Mean annual flow was positively related to minimum flows, suggesting that potential future declines in mean annual flows will correspond with declines in minimum flows. The most important landscape variables for predicting low flow metrics were precipitation, percent snow, potential evapotranspiration, soils, and drainage area. Perennial streams in the UCRB that have high minimum-flow variability and low mean flows are likely to be most susceptible to increasing streamflow intermittency in the future.

  15. Overland flow generation mechanisms affected by topsoil treatment: Application to soil conservation

    González Paloma, Hueso; Juan Francisco, Martinez-Murillo; Damian, Ruiz-Sinoga Jose; Hanoch, Lavee


    Hortonian overland-flow is responsible for significant amounts of soil loss in Mediterranean geomorphological systems. Restoring the native vegetation is the most effective way to control runoff and sediment yield. During the seeding and plant establishment, vegetation cover may be better sustained if soil is amended with an external source. Four amendments were applied in an experimental set of plots: straw mulching (SM); mulch with chipped branches of Aleppo Pine (Pinus halepensis L.) (PM); TerraCotten hydroabsobent polymers (HP); sewage sludge (RU); and control (C). Plots were afforested following the same spatial pattern, and amendments were mixed with the soil at the rate 10 Mg ha-1. This research demonstrates the role played by the treatments in overland flow generation mechanism (runoff, overland flow and soil moisture along the soil profile). The general overland flow characteristics showed that in the C plots the average overland flow was 8.0 ± 22.0 l per event, and the HP plots produced a similar mean value (8.1 ± 20.1 l). The average overland flow per event was significantly less for soil amended with SM, PM or RU (2.7 ± 8.3 l; 1.3 ± 3.5 l and 2.2 ± 5.9 l, respectively). There was a similar trend with respect to the maximum overland flow. The mean sediment yield per event was relatively high in the C and HP plots (8.6 ± 27.8 kg and 14.8 ± 43.4 kg, respectively), while significantly lower values were registered in the SM, PM and RU plots (0.4 ± 1.0 kg; 0.2 ± 0.3 kg and 0.2 ± 0.3 kg, respectively). Very similar trends were found for the maximum sediment yield. Regarding to the soil moisture values, there was a difference in the trends between the C and HP plots and the SM, PM and RU plots. In the C and HP plots the general trend was for a decrease in soil moisture downward through the soil profile, while in the SM, PM and RU plots the soil moisture remained relatively constant or increased, except for the RU treatment in which the soil moisture

  16. Modeling two-dimensional water flow and bromide transport in a heterogeneous lignitic mine soil

    Buczko, U.; Gerke, H.H. [Brandenburg University of Technology, Cottbus (Germany)


    Water and solute fluxes in lignitic mine soils and in many other soils are often highly heterogeneous. Here, heterogeneity reflects dumping-induced inclined structures and embedded heterogeneous distributions of sediment mixtures and of lignitic fragments. Such two-scale heterogeneity effects may be analyzed through the application of two-dimensional models for calculating water and solute fluxes. The objective of this study was to gain more insight to what extent spatial heterogeneity of soil hydraulic parameters contributes to preferential flow at a lignitic mine soil. The simulations pertained to the 'Barenbrucker Hohe' site in Germany where previously water fluxes and applied tracers had been monitored with a cell lysimeter, and from where a soil block had been excavated for detailed two-dimensional characterization of the hydraulic parameters using pedotransfer functions. Based on those previous studies, scenarios with different distributions of hydraulic parameters were simulated. The results show that spatial variability of hydraulic parameters alone can hardly explain the observed flow patterns. The observed preferential flow at the site was probably caused by additional factors such as hydrophobicity, the presence of root channels, anisotropy in the hydraulic conductivity, and heterogeneous root distributions. To study the relative importance of these other factors by applying two-dimensional flow models to such sites, the experimental database must be improved. Single-continuum model approaches may be insufficient for such sites.

  17. Assessing geotechnical centrifuge modelling in addressing variably saturated flow in soil and fractured rock.

    Jones, Brendon R; Brouwers, Luke B; Van Tonder, Warren D; Dippenaar, Matthys A


    The vadose zone typically comprises soil underlain by fractured rock. Often, surface water and groundwater parameters are readily available, but variably saturated flow through soil and rock are oversimplified or estimated as input for hydrological models. In this paper, a series of geotechnical centrifuge experiments are conducted to contribute to the knowledge gaps in: (i) variably saturated flow and dispersion in soil and (ii) variably saturated flow in discrete vertical and horizontal fractures. Findings from the research show that the hydraulic gradient, and not the hydraulic conductivity, is scaled for seepage flow in the geotechnical centrifuge. Furthermore, geotechnical centrifuge modelling has been proven as a viable experimental tool for the modelling of hydrodynamic dispersion as well as the replication of similar flow mechanisms for unsaturated fracture flow, as previously observed in literature. Despite the imminent challenges of modelling variable saturation in the vadose zone, the geotechnical centrifuge offers a powerful experimental tool to physically model and observe variably saturated flow. This can be used to give valuable insight into mechanisms associated with solid-fluid interaction problems under these conditions. Findings from future research can be used to validate current numerical modelling techniques and address the subsequent influence on aquifer recharge and vulnerability, contaminant transport, waste disposal, dam construction, slope stability and seepage into subsurface excavations.

  18. Riparian woodland encroachment following flow regulation: a comparative study of Mediterranean and Boreal streams

    Dolores Bejarano M.


    Full Text Available Water development accompanying mankind development has turned rivers into endangered ecosystems. Improving the understanding of ecological responses to river management actions is a key issue for assuring sustainable water management. However, few studies have been published where ecological metrics have been quantified in response to various degrees of flow alteration. In this work, changes in natural distribution of trees and shrubs within the riparian corridor (as indicator of the ecological status of the fluvial ecosystem were quantified at multiple sites along a flow alteration gradient (as indicator of impact along two regulated river reaches, one Boreal and the other Mediterranean, each downstream of a dam. Based on the obtained relationships we evaluated differences in response trends related to local physico-climatic factors of the two biomes and regarding to differing life-forms. Woody vegetation establishment patterns represented objective indicators of ecological responses to flow alteration. We found different responses between life-forms. Both trees and shrubs migrated downwards to the channel after dam closure, but shrubs were most impacted under higher degrees of flow alteration in terms of lateral movement. In addition, our results show clear longitudinal recovery trends of natural patterns of tree and shrub distribution corresponding to a decrease in intensity of hydrologic alteration in the Boreal river. However, vegetation encroachment persisted along the entire Mediterranean study reach. This may result from a relatively low gradient of decrease of hydrologic alteration with distance from the dam, coupled with other overlapping pressures and the mediating effect of physico-climatic characteristics on vegetation responses.

  19. Characterizing soil preferential flow using iodine--starch staining experiments and the active region model

    Sheng, Feng; Wang, Kang; Zhang, Renduo; Liu, Hui-Hai


    Thirteen iodine-starch staining experiments with different boundary conditions and measurement scales were conducted at two sites to study preferential flow processes in natural unsaturated soils. Digital imaging analyses were implemented to obtain the corresponding preferential flow patterns. The test results are used to evaluate a recently proposed active region model in terms of its usefulness and robustness for characterizing unsaturated flow processes at field scale. Test results provide useful insights into flow patterns in unsaturated soils. They show that flow pattern depends on the top boundary condition. As the total infiltrating-water depth increased form 20 mm to 80 mm for the 100 x 100 cm{sup 2} plots, the corresponding flow pattern changed from few preferential flow paths associated with a relatively small degree of stained coverage and a small infiltration depth, to a pattern characterized by a higher stained coverage and a larger infiltration depth, and to (finally) a relatively homogeneous flow pattern with few unstained area and a much larger infiltration depth. Test results also show that the preferential flow pattern became generally more heterogeneous and complex for a larger measurement scale (or size of infiltration plot). These observations support the general idea behind the active region model that preferential flow pattern in unsaturated soils are dynamic and depend on water flow conditions. Further analyses of the test results indicate that the active-region model is able to capture the major features of the observed flow pattern at the scale of interest, and the determined parameter values do not significantly depend on the test conditions (initial water content and total amount of infiltrating water) for a given test site. This supports the validity of the active region model that considers that parameter to be a property of the corresponding unsaturated soil. Results also show that some intrinsic relation seems to exist between active


    WANGSuo-fang; LILi-guo; WUGuo-chuan


    The flow and the temperature in the threestream mixing flow of the lobed nozzle mixer-ejector with double-wall diffuser are numerically investigated. The domain of computation is divided into sub-domalns according to the shapes of the double-plate and lobed nozzle. The three-dimensional body-fitted coordinated grids are generated respectively in these sub-domains by solving Lapalace's equations. Grids are dense on the boundaries and orthogonal at the lobe. The grids of all sub-domains compose the whole grid of the domain. In order to avoid the divergence of the computation as the serious non-orthogonality of the grid from the lobe, the co-located grid, SIMPLEC and Chen-Kim modified k-εturbulence model are applied. The great viscosity, the linear and simultaneous cooperation under-relaxation factors are used to solve the coupling of the fluid and solid. Results show that the air is ejected into the double wall section to form the cooling flow. The wall temperature of the double-wall diffuser is lower than that of the single-wall diffuser. The average wall temperature goes down as the diffuser angle increases at the range of 0~5°,otherwise, the result at the range of 5~10°is opposite.

  1. Measurement of dissolved Cs-137 in stream water, soil water and groundwater at Headwater Forested Catchment in Fukushima after Fukushima Dai-ichi Nuclear Power Plant Accident

    Iwagami, Sho; Tsujimura, Maki; Onda, Yuichi; Sakakibara, Koichi; Konuma, Ryohei; Sato, Yutaro


    Radiocesium migration from headwater forested catchment is important perception as output from the forest which is also input to the subsequent various land use and downstream rivers after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In this study, dissolved Cs-137 concentration of stream water, soil water and groundwater were measured. Observations were conducted at headwater catchment in Yamakiya district, located 35 km northwest of FDNPP from April 2014 to November 2015. Stream water discharge was monitored and stream water samples were taken at main channel and sub channel. Stream water discharge was monitored by combination of parshallflume and v-notch weir. Stream water was sampled manually at steady state condition in 3-4 month interval and also intense few hours interval sampling were conducted during rainfall events using automated water sampler. Around the sub channel, it is found that there is a regularly saturated area at the bottom of the slope, temporary saturated area which saturate during the rainy season in summer and regularly dry area. 6 interval cameras were installed to monitor the changing situation of saturated area. Suction lysimeters were installed at three areas (regularly saturated area, temporary saturated area and dry area) for sampling soil water in depth of 0.1 m and 0.3 m. Boreholes were installed at three points along the sub channel. Three boreholes with depth of 3 m, 5 m and 10 m were installed at temporary saturated area, 20 m upstream of sub channel weir. Another three boreholes with depth of 3 m, 5 m and 10 m were installed at dry area, 40 m upstream of sub channel weir. And a borehole with depth of 20 m was installed at ridge of sub catchment, 52 m upstream of sub channel weir. Groundwater was sampled by electrically powered pump and groundwater level was monitored. Also suction-free lysimeter was installed at temporary saturated area for sampling the near surface subsurface water. Soil water samples were collected

  2. Monitoring water flow process based on streaming potential forward model in unsaturated zone%基于流动电位正演模型的非饱和带水流过程监测

    杨磊; 周启友


    为了获取非饱和带水流过程的信息,借助流动电位正演模型,通过数值实验探讨非降雨和降雨两种条件下非饱和带流动电位和水流过程的关系,然后用南京中山植物园试验场地野外观测的流动电位和张力数据加以对比和验证.野外试验表明:流动电位可以有效地反映非饱和带水流过程.在夏季无降雨入渗的条件下,日周期变化的地表地下温度差导致水分的运动,流动电位准确地指示了非饱和带含水量和毛细压力的变化情况,从而指示出了水分运移的方向;在夏季有降雨入渗的条件下,降雨锋面推进之处,含水量和流动电位同时有明显的响应,进而根据不同位置的流动电位对降雨入渗响应的时刻差,直接求出入渗锋面的推进速度.%Based on streaming potential forward model, the relationship between streaming potential and water flow process in unsaturated zone was studied in no rainfall condition and rainfall condition. The field data obtained in the research site of Zhongshan Botanical Garden in Nanjing was applied to compare with the results of numerical experiments. Field experiments showed that streaming potential method was efficient to detect the water flow process in unsaturated zone. If rainfall events didn't happen for a long time, the daily variations of temperature difference between soil surface and subsurface might induce water movements. By monitoring streaming potential signals in the field, the variations of water content and capillary head could be indicated and the water flow direction was pointed out at the same time. When a rainfall event happened, the water content and streaming potential were responsible for the migration of infiltration front immediately. According to the responses of different depth at different time, the movement velocity of infiltration front could be calculated directly.

  3. Laboratory study on streaming potential for exploring underground water flow; Shitsunai jikken ni yoru ryudo den`i wo mochiita mizu michi tansa no kanosei no kento

    Sato, H.; Shima, H. [Oyo Corp., Tokyo (Japan)


    To investigate a possibility of exploration of underground water flow as well as to grasp the underground fluid flow by measuring streaming potential at the ground surface, some experiments were conducted using a model unit by considering the difference of permeability. For this experimental unit, water is driven by adding head difference between the polyethylene vessel filled with water and the experimental water tank. The size of water tank is 350{times}160 mm with a height of 160 mm. Twenty platinum electrodes are set on the cover of water tank. Toyoura standard sand and Kanto loam were used for the experiments. For the experiments, fluid was injected in various combined models by considering the permeability, to measure the streaming potential. As a result, it was explained by the streaming potential that the fluid flows in a form of laminar flow in the experimental water tank, and that the movement of fluid in the Kanto loam is quite slow. It was also confirmed that the streaming potential method is an effective technique for grasping the movement of fluid. 3 refs., 8 figs.

  4. Differences in stream flow in relation to changes in land cover: a comparative study in two sub-Mediterranean mountain catchments.

    Lana-Renault, N.; Latron, J.; Karssenberg, D.J.; Serrano-Muela, P.; Regüés, D.; Bierkens, M.F.P.


    The stream flow response of two neighboring catchments in the central Spanish Pyrenees was compared for 26 rainstorms covering both catchments: one catchment (2.84 km2) was extensively used for agriculture in the past, and the other (0.92 km2) is covered by dense natural forest. Their similarity in

  5. Temporal variations in the flow of a large Antarctic ice-stream controlled by tidally induced changes in the subglacial water system

    S. H. R. Rosier


    7 × 109 m2d-1, with sliding law exponents m = 3 and q =10. Coupled model results show the presence of tides result in a ~ 12% increase in mean surface velocity. Observations of tidally-induced variations in flow of ice-streams provide stronger constraints on basal sliding processes than provided by any other set of measurements.

  6. Attribution of changes in stream flow to land use change and climate change in a mesoscale tropical catchment in Java, Indonesia

    Marhaento, Hero; Booij, Martijn J.; Hoekstra, Arjen Y.


    Changes in the stream flow of the Samin catchment (277.9 km2) in Java, Indonesia, have been attributed to land use change and climate change. Hydroclimatic data covering the period 1990-2013 and land use data acquired from Landsat satellite imageries for the years 1994 and 2013 were analysed. A quan

  7. An Application of Value Stream Mapping in Production Flow Analysis: A lean approach in An Automotive Industry

    Krushnaraj Bodana


    Full Text Available Lean manufacturing deals with a manufacturing process improvement based on the fundamental goal of Toyota production system in order to minimize or eliminate waste while maximizing production flow. Today in a highly competitive local and global market, it is very much crucial to satisfy the changing demand of the customers. Thus, in today’s manufacturing industry there is an increased focus to produce the right product at right time. The prime objective of this paper to apply a significant lean manufacturing tool know as Value Stream Mapping (VSM. To fulfil this objective a fundamental principles of lean were implemented and VSM was generated to analyse the production flow at an automotive industry and improve the current operating condition to overcome the difficulties with current state of work through time study, Takt time calculation, modifying work cell layout. And based on the future state of VSM, final results showed that by implementing this lean techniques, Production Lead-time (PLT decreased from 7.6 days to 3.2 days, and the cycle time is decrease up to 73%.

  8. Tumbling, stretching and cross-stream migration of polymers in rectilinear shear flow from dissipative particle dynamics simulations

    Danioko, Sidy; Laradji, Mohamed


    Solutions of flexible polymer chains with harmonic bonds undergoing rectilinear flow in slit pores are investigated via dissipative particle dynamics (DPD) simulations. We found that when DPD with low Schmidt number (Sc∼1) is used, the polymer chains tend to migrate across the streamlines towards the walls. However, a cross-stream migration towards the centerline is observed when DPD with relatively high values of Schmidt number (Sc∼10) is used. The effect of chain length and Weissenberg number, defined as Wi=Γ˙τrel, where Γ˙ and τrel are the shear rate and polymer longest relaxation time, respectively, are investigated. The polymer chains exhibit a large number of orientational and extensional fluctuations, with the distributions of both latitude and azimuthal angles exhibiting power-law decays in agreement with experiments, theory and previous simulations. The polymer chains exhibit tumbling kinetics characterized by an exponential distribution of tumbling times. The characteristic time scale is proportional to the longest relaxation time of the polymer chains at equilibrium. The power spectral density of the extension, while monotonically decaying for large chain length or large Weissenberg number, exhibits a shallow peak for short chains, implying that shear flow induces nearly repetitive tumbling of the polymer chains. The time scale corresponding to the peak of the extension power spectral density is also proportional to the longest chain relaxation time.

  9. Antibiogram of isolated bacteria from Omisanjana hand-dug well water and flowing stream

    O.A. Toba


    Full Text Available Water samples were obtained from ten (10 wells around Omisanjana stream, Ado-Ekiti to determine the microbiological and physicochemical quality. The samples were analyzed for the total bacterial and coliform count and the isolated organisms were identified using standard techniques which were further screened for susceptibility to various antibiotics commonly used in the community. The total bacterial count ranged from 2.6 x 103 to 10.9 x 104 CFU/ml and the total coliform counts ranging from 3.0 x 102 to 9.3 x104 CFU/ml; which exceeded the WHO standard for drinking water. The organisms isolated belonged to eleven genera, among which Staphylococcus aureus showed highest frequency (24.6% while Acinetobacter spp. with least frequency (4.3%. The physicochemical properties of the water accord with the WHO standard with pH range of (6.2-71, temperature (26.9-29.2, turbidity (-0.8 - 6.5 NTU, conductivity (0.04-0.23µS/cm, total hardness (14-80 mgL-1, TDS (34 to166 mgL-1 and TSS of (29 to 122 mgL-1. Higher level of resistance to the antibiotics tested was more prominent in the E.coli than in Staphylococcus aureus. Although some strains were susceptible to some commonly used antibiotics, but the resistant bacteria encountered pose a serious public health risk especially with the increasing rate of transfer of resistant genes from one bacterium to another. There is therefore need to treat water obtained from wells in the community to make it safe for domestic use.

  10. El-Niño/Southern Oscillation (ENSO) influences on monthly NO 3 load and concentration, stream flow and precipitation in the Little River Watershed, Tifton, Georgia (GA)

    Keener, V. W.; Feyereisen, G. W.; Lall, U.; Jones, J. W.; Bosch, D. D.; Lowrance, R.


    SummaryAs climate variability increases, it is becoming increasingly critical to find predictable patterns that can still be identified despite overall uncertainty. The El-Niño/Southern Oscillation is the best known pattern. Its global effects on weather, hydrology, ecology and human health have been well documented. Climate variability manifested through ENSO has strong effects in the southeast United States, seen in precipitation and stream flow data. However, climate variability may also affect water quality in nutrient concentrations and loads, and have impacts on ecosystems, health, and food availability in the southeast. In this research, we establish a teleconnection between ENSO and the Little River Watershed (LRW), GA., as seen in a shared 3-7 year mode of variability for precipitation, stream flow, and nutrient load time series. Univariate wavelet analysis of the NINO 3.4 index of sea surface temperature (SST) and of precipitation, stream flow, NO 3 concentration and load time series from the watershed was used to identify common signals. Shared 3-7 year modes of variability were seen in all variables, most strongly in precipitation, stream flow and nutrient load in strong El Niño years. The significance of shared 3-7 year periodicity over red noise with 95% confidence in SST and precipitation, stream flow, and NO 3 load time series was confirmed through cross-wavelet and wavelet-coherence transforms, in which common high power and co-variance were computed for each set of data. The strongest 3-7 year shared power was seen in SST and stream flow data, while the strongest co-variance was seen in SST and NO 3 load data. The strongest cross-correlation was seen as a positive value between the NINO 3.4 and NO 3 load with a three-month lag. The teleconnection seen in the LRW between the NINO 3.4 index and precipitation, stream flow, and NO 3 load can be utilized in a model to predict monthly nutrient loads based on short-term climate variability

  11. Association of dissolved mercury with dissolved organic carbon in U.S. rivers and streams: The role of watershed soil organic carbon

    Stoken, Olivia M.; Riscassi, Ami L.; Scanlon, Todd M.


    Streams and rivers are important pathways for the export of atmospherically deposited mercury (Hg) from watersheds. Dissolved Hg (HgD) is strongly associated with dissolved organic carbon (DOC) in stream water, but the ratio of HgD to DOC is highly variable between watersheds. In this study, the HgD:DOC ratios from 19 watersheds were evaluated with respect to Hg wet deposition and watershed soil organic carbon (SOC) content. On a subset of sites where data were available, DOC quality measured by specific ultra violet absorbance at 254 nm, was considered as an additional factor that may influence HgD:DOC . No significant relationship was found between Hg wet deposition and HgD:DOC, but SOC content (g m-2) was able to explain 81% of the variance in the HgD:DOC ratio (ng mg-1) following the form: HgD:DOC=17.8*SOC-0.41. The inclusion of DOC quality as a secondary predictor variable explained only an additional 1% of the variance. A mathematical framework to interpret the observed power-law relationship between HgD:DOC and SOC suggests Hg supply limitation for adsorption to soils with relatively large carbon pools. With SOC as a primary factor controlling the association of HgD with DOC, SOC data sets may be utilized to predict stream HgD:DOC ratios on a more geographically widespread basis. In watersheds where DOC data are available, estimates of HgD may be readily obtained. Future Hg emissions policies must consider soil-mediated processes that affect the transport of Hg and DOC from terrestrial watersheds to streams for accurate predictions of water quality impacts.

  12. Relation between Streaming Potential and Streaming Electrification Generated by Streaming of Water through a Sandwich-type Cell

    Maruyama, Kazunori; NIKAIDO, Mitsuru; Hara, Yoshinori; Tanizaki, Yoshie


    Both streaming potential and accumulated charge of water flowed out were measured simultaneously using a sandwich-type cell. The voltages generated in divided sections along flow direction satisfied additivity. The sign of streaming potential agreed with that of streaming electrification. The relation between streaming potential and streaming electrification was explained from a viewpoint of electrical double layer in glass-water interface.

  13. Relation between Streaming Potential and Streaming Electrification Generated by Streaming of Water through a Sandwich-type Cell

    Maruyama, Kazunori; NIKAIDO, Mitsuru; Hara, Yoshinori; Tanizaki, Yoshie


    Both streaming potential and accumulated charge of water flowed out were measured simultaneously using a sandwich-type cell. The voltages generated in divided sections along flow direction satisfied additivity. The sign of streaming potential agreed with that of streaming electrification. The relation between streaming potential and streaming electrification was explained from a viewpoint of electrical double layer in glass-water interface.

  14. Stream flow rate measurement using tracer techniques at the Kemubu Agricultural Development Authority (KADA), Kelantan

    Daud Mohammad; Abd Razak Hamzah; Wan Abd Aziz Wan Mohamad; Juhari Yusoff; Wan Zakaria Wan Mohd Tahir


    Measuring the flow rate of a water course is one of the basic operations in hydrology, being of general relevance to water problems and of particular importance in the planning of water control schemes. The techniques commonly used in streamflow gauging are either by a current meter of tracer dilution method. This paper describes the latter technique in which radioisotope Tc-99m was used as a tracer in streamflow measurements performed in 1983 in a few selected irrigation canals and pump house under the Kemubu Agriculture Development Authority (KADA), Kelantan. Total count technique and peak-to-peak method were adopted in this study. (author).

  15. Genesis and mechanism of rainfall-induced hyperconcentrated flows in granular soils

    Della Sala, Maria


    2012-2013 Heavy rainfall on steep hillslopes may cause either shallow landslides or soil superficial erosion and different flow-type phenomena may originate in adjacent/overlapping source areas. Consequently, great amount of water and debris can be conveyed at the outlet of steep mountain basins where huge consequences are often registered. Recent studies outline that first-time shallow slides may turn into debris flows or debris avalanches; conversely, slope instabilities initiated by ...

  16. Linking soil moisture balance and source-responsive preferential flow models for estimating groundwater recharge

    Cuthbert, M. O.; Mackay, R.; Nimmo, J. R.


    Results are presented of a detailed study into the vadose zone and shallow water table hydrodynamics of a fieldsite in Shropshire, UK. Tensiometry reveals that the loamy sand topsoil wets up via macropore flow and subsequent redistribution of moisture into the soil matrix. However, recharge does not occur until near-positive pressures are achieved at the top of the glaciofluvial outwash material that underlies the topsoil, about 1 m above the water table. Once this occurs, very rapid water table rises follow. This threshold behaviour is attributed to the vertical discontinuity in the macropore system due to seasonal ploughing of the topsoil, and a lower permeability plough/iron pan restricting matrix flow between the topsoil and the lower outwash deposits. Thus, although the wetting process in the topsoil is highly complex, a soil moisture balance model (SMBM) is shown to be skilful in predicting the initiation of preferential flow from the base of the topsoil into the lower outwash horizon. The rapidity of the response at the water table suggests that Stokes type film flow rather than Richards type capillarity dominated flow is occurring and this conjecture is tested using a range of numerical models. A variation of the source-responsive model proposed by Nimmo (2010) is shown to reproduce the observed water table dynamics well, when linked to a SMBM as the source of recharge from the topsoil. The results reveal new insights into preferential flow processes in cultivated soils. If the conceptual and numerical models can be shown to be transferable to other ploughed soils, it promises to be a very useful and practical approach to accounting for preferential flow in studies of groundwater recharge estimation. Nimmo, J. R. (2010). Theory for Source-Responsive and Free-Surface Film Modeling of Unsaturated Flow. Vadose Zone Journal, 9, 295-306.

  17. MOD_FreeSurf2D: a Surface Fluid Flow Simulation Model for Rivers, Streams, and Shallow Estuaries

    Martin, N.; Gorelick, S. M.


    The MOD_FreeSurf2D, Modular Free Surface Flow in Two-Dimensions, computer model simulates free surface fluid flow in streams, rivers, and shallow estuaries under the assumptions of a well-mixed water column, a small water depth to width ratio, and a hydrostatic pressure distribution. The dependent variables in the model are free surface elevation, which provides total water depth, and fluid velocity. Primary advantages of MOD_FreeSurf2D relative to other two-dimensional models are a stable and computationally efficient numerical representation and a transparent representation of wetting and drying of the simulation domain. MOD_FreeSurf2D approximates the depth-averaged, shallow water equations with a finite volume, semi-implicit, semi-Lagrangian numerical representation similar to the TRIM method (Casulli, 1990; Casulli and Cheng, 1992; Casulli, 1999). The semi-implicit, semi-Lagrangian approach is computationally efficient because time steps can exceed the Courant-Friedrich-Lewy (CFL) stability criterion without significant accuracy degradation (Robert, 1982; Casulli, 1990). The rectangular, Arakawa C-grid, finite-volume layout allows flooding and drying in response to changing flow conditions without prior channel specification or closed boundary specification. Open boundary conditions available in MOD_FreeSurf2D are specified flux, specified total water depth, specified velocity, radiation free surface, and radiation velocity. MOD_FreeSurf2D requires initial topography, undisturbed water depth, and Manning's roughness coefficient. MOD_FreeSurf2D simulated results are shown to converge to the semi-empirical solution for a simple straight channel case. Two applications demonstrate the accuracy of MOD_FreeSurf2D. The first application is the evolution of water depth in the dambreak-style flume experiment of Bellos et al. (1992). In this case, MOD_FreeSurf2D accurately simulates the changing water depth in the flume during the experiment and models the wetting of

  18. A soil flowing characteristics monitoring method in planetary drilling and coring verification experiments

    Tang, Junyue; Quan, Qiquan; Jiang, Shengyuan; Chen, Chongbin; Yuan, Fengpei; Deng, Zongquan


    Some type of piercing into the subsurface formation is required in future planetary explorations to enhance the understanding of early stars' geological evolution and the origin of life. Compared with other technical methods, drilling & coring, only utilizing the compound locomotion of rotation and penetration, can sample the subsurface soil relatively efficient and convenient. However, given the uncertain mechanical properties of planetary soil, drilling state signals should be monitored online to improve the robustness of drilling system and avoid potential drilling faults. Since the flowing characteristics of interacted soil, such as removal volume, coring height, removal velocity and accumulation angle, directly reveal the drilling conditions, they are enhancing resources to comprehend the sampling phenomenon and can be used to help control the drill tool. This paper proposed a novel soil flowing characteristics (SFC) monitoring method by applying an industrial camera to record the flowing characteristics of removed cuttings and by utilizing an ultrasonic sensor into the hollow auger to monitor the sampled core. Experiments in one typical lunar regolith simulant indicate that the monitored SFC accurately reflects the interaction between the drill tool and soil.

  19. Water movement and isoproturon behaviour in a drained heavy clay soil: 1. Preferential flow processes

    Haria, A. H.; Johnson, A. C.; Bell, J. P.; Batchelor, C. H.


    The processes and mechanisms that control pesticide transport from drained heavy clay catchments are being studied at Wytham Farm (Oxford University) in southern England. In the first field season field-drain water contained high concentrations of pesticide. Soil studies demonstrated that the main mechanism for pesticide translocation was by preferential flow processes, both over the soil surface and through the soil profile via a macropore system that effectively by-passed the soil matrix. This macropore system included worm holes, shrinkage cracks and cracks resulting from ploughing. Rainfall events in early winter rapidly created a layer of saturation in the A horizon perched above a B horizon of very low hydraulic conductivity. Drain flow was initiated when the saturated layer in the A horizon extended into the upper 0.06m of the soil profile; thereafter water moved down slope via horizontal macropores possibly through a band of incorporated straw residues. These horizontal pathways for water movement connected with the fracture system of the mole drains, thus feeding the drains. Overland flow occurred infrequently during the season.

  20. Soil morphology of a debris flow chronosequence in a coniferous forest, southern California, USA

    Turk, J.K.; Goforth, B.R.; Graham, R.C.; Kendrick, K.J.


    Soils on a series of debris flow deposits, ranging from coniferous forest. Ages of the deposits were assessed using dendrochronology. Morphologic trends in the organic horizons included a thickening of the humus form over time, along with the development of Fm and Hr horizons. The humus forms underwent a progression from Mormodors (20??years old), to Hemimors (26-101??years old), and finally Lignomors (163??years old) and Resimors (184-244??years old). Changes in physical properties of the uppermost mineral horizons as a function of increasing age included a decrease in the volume of coarse fragments, a linear decrease in bulk density, and a darkening and reddening of the soil color. No significant soil development took place in the subsoil during the time span of this chronosequence. The soils described were classified as Typic Xerofluvents and Typic Xerorthents (Regosols and Leptosols). Buried A horizons were observed in many of the soils. Where the A horizons could be linked to dendrochronology to assess the age of the buried surface, we found that the properties of the buried A horizons do not serve as a good indicator of the age of the surface. This study suggests rapid development of the humus form profile (organic horizons and A horizon) following debris flow deposition and rapid degradation of these horizons when the debris flow surface is buried. ?? 2008 Elsevier B.V.

  1. Scaling preferential flow processes in agricultural soils affected by tillage and trafficking at the field scale

    Filipović, Vilim; Coquet, Yves


    There is an accumulation of experimental evidences that agricultural soils, at least the top horizons affected by tillage practices, are not homogeneous and present a structure that is strongly dependent on farming practices like tillage and trafficking. Soil tillage and trafficking can create compacted zones in the soil with hydraulic properties and porosity which are different from those of the non-compacted zones. This spatial variability can strongly influence transport processes and initiate preferential flow. Two or three dimensional models can be used to account for spatial variability created by agricultural practices, but such models need a detailed assessment of spatial heterogeneity which can be rather impractical to provide. This logically raises the question whether and how one dimensional model may be designed and used to account for the within-field spatial variability in soil structure created by agricultural practices. Preferential flow (dual-permeability) modelling performed with HYDRUS-1D will be confronted to classical modelling based on the Richards and convection-dispersion equations using HYDRUS-2D taking into account the various soil heterogeneities created by agricultural practices. Our goal is to derive one set of equivalent 1D soil hydraulic parameters from 2D simulations which accounts for soil heterogeneities created by agricultural operations. A field experiment was carried out in two phases: infiltration and redistribution on a plot by uniform sprinkle irrigation with water or bromide solution. Prior to the field experiment the soil structure of the tilled layer was determined along the face of a large trench perpendicular to the tillage direction (0.7 m depth and 3.1 m wide). Thirty TDR probes and tensiometers were installed in different soil structural zones (Δ compacted soil and Γ macroporous soil) which ensured soil water monitoring throughout the experiment. A map of bromide was constructed from small core samples (4 cm diam

  2. Heterogeneous water flow and pesticide transport in cultivated sandy soils : description of model concepts

    Leistra, M.; Boesten, J.J.T.I.


    There is ample experimental evidence that complications in water flow and pesticide transport can occur in cultivated humic-sandy and loamy-sandy soils. As a result, pesticide leaching to groundwater and water courses can be higher than expected. We made an inventory of mechanistic/deterministic mod

  3. Water flow induced transport of Pseudomonas fluorescens cells through soil columns as affected by inoculant treatment

    Hekman, W.E.; Heijnen, C.E.; Trevors, J.T.; Elsas, van J.D.


    Water flow induced transport of Pseudomonas fluorescens cells through soil columns was measured as affected by the inoculant treatment. Bacterial cells were introduced into the topsoil of columns, either encapsulated in alginate beads of different types or mixed with bentonite clay in concentrations

  4. Preferential flow of bromide, bentazon, and imidacloprid in a Dutch clay soil

    Scorza Júnior, R.P.; Smelt, J.H.; Boesten, J.J.T.I.; Hendriks, R.F.A.; Zee, van der S.E.A.T.M.


    Leaching to ground water and tile drains are important parts of the environmental assessment of pesticides. The aims of the present study were to (i) assess the significance of preferential flow for pesticide leaching under realistic worst-case conditions for Dutch agriculture (soil profile with thi

  5. Water flow induced transport of Pseudomonas fluorescens cells through soil columns as affected by inoculant treatment

    Hekman, W.E.; Heijnen, C.E.; Trevors, J.T.; Elsas, van J.D.


    Water flow induced transport of Pseudomonas fluorescens cells through soil columns was measured as affected by the inoculant treatment. Bacterial cells were introduced into the topsoil of columns, either encapsulated in alginate beads of different types or mixed with bentonite clay in concentrations

  6. Relationships between basic soils-engineering equations and basic ground-water flow equations

    Jorgensen, Donald G.


    The many varied though related terms developed by ground-water hydrologists and by soils engineers are useful to each discipline, but their differences in terminology hinder the use of related information in interdisciplinary studies. Equations for the Terzaghi theory of consolidation and equations for ground-water flow are identical under specific conditions. A combination of the two sets of equations relates porosity to void ratio and relates the modulus of elasticity to the coefficient of compressibility, coefficient of volume compressibility, compression index, coefficient of consolidation, specific storage, and ultimate compaction. Also, transient ground-water flow is related to coefficient of consolidation, rate of soil compaction, and hydraulic conductivity. Examples show that soils-engineering data and concepts are useful to solution of problems in ground-water hydrology.

  7. Effects of preferential flow on soil-water and surface runoff in a forested watershed in China

    Jinhua CHENG; Hongjiang ZHANG; Youyan ZHANG; Yuhu SHI; Yun CHENG


    Preferential flow is a runoff mechanism intermediate between matrix flow and surface flow, transmitting water at high velocity through the subsurface zone. To assess the effect of preferential flow on soil-water flow and surface runoff in a forested watershed, precipitation and volumes of preferential flow, matrix flow and surface runoff were measured over a period of four years in a forested watershed in the Three Gorges area of southern China. Results show that preferential-flow hydrographs have gentler rises and steeper recessions than those for matrix flow and surface runoff. Preferential flow as a percentage of soil-water flow ranged from 2.40% to 8.72% and the maximum preferential-flow velocity exceeded as much as 5600 times that of matrix flow. This shows that preferential flow plays an important role in the movement of soil water. Preferential flow has a significant effect on peak surface runoff by increasing the surface runoff rate and accelerating the appearance of peak surface runoff. Preferential flow can also prolong the duration of surface runoff. Surface runoff was observed to be positively correlated with preferential flow. The greater the sum of rainfall amount and antecedent precipitation is, the greater the effect of preferential flow on surface runoff is.

  8. Accounting for intracell flow in models with emphasis on water table recharge and stream-aquifer interaction. 1. Problems and concepts

    Jorgensen, D.G.; Signor, D.C.; Imes, J.L.


    One method of modeling multiple sources and sinks is to determine the net recharge per cell. For example, for a model cell containing both a sink and recharge through the water table, the amount of recharge should be reduced by the ratio of the area of influence of the sink within the cell to the area of the cell. The reduction is the intercepted portion of the recharge. In a multilayer model this amount is further reduced by a proportion factor, which is a function of the depth of the flow lines from the water table boundary to the internal sink. A gaining section of a stream is a typical sink. The aquifer contribution to a gaining stream can be conceptualized as having two parts; the first part is the intercepted lateral flow from the water table and the second is the flow across the streambed due to differences in head between the water level in the stream and the aquifer below. The amount intercepted is a function of the geometry of the cell, but the amount due to difference in head across the stream bed is largely independent of cell geometry. -from Authors

  9. Identification of effective flow processes and properties from virtual soils using inverse modelling

    Schelle, H.; Iden, S. C.; Schlüter, S.; Vogel, H.-J.; Durner, W.


    Simulation of water flow and solute transport in unsaturated soils requires accurate knowledge of soil hydraulic properties. This study aims at developing strategies for deriving the flow and transport parameters for effective models at the scale of an agricultural field. Although hydraulic properties can be estimated from field observations under atmospheric boundary conditions by inverse modeling, the spatial heterogeneity of soil hydraulic properties within a field is known to strongly influence both local observations and the average behavior of the system. To assess the impact of individual or combined structural components on the water dynamics within the system, the interdisciplinary research group INVEST performs water flow simulations in complex two- and three-dimensional virtual realities, representing cultivated soils with spatial heterogeneity on multiple scales. Numerical simulations with a high spatiotemporal resolution yield synthetic datasets of internal state variables and fluxes. These data mimic measurements which could be recorded by typical instruments in a field soil. The simulated datasets are used to analyze the influence of the soil structures on the variability of measured data and to develop and test parameter estimation procedures. The central questions being addressed in this contribution are: (i) How big is the lateral variability of the measured data? (ii) How can within-field structures be related to the effective model parameters that are needed to predict average water dynamics at the field scale? (iii) How do the estimated hydraulic properties depend on measurement type and location? And (iv) what is the impact of the variability of the estimated effective hydraulic properties on the assessment of the soil water budget? To answer these questions we evaluate different data sets in terms of information content and usefulness for identifying suitable effective models and effective model parameters. The simulations show that a general

  10. Multi-phase flow modeling of soil contamination and soil remediation.

    Dijke, van M.I.J.


    In this thesis multi-phase flow models are used to study the flow behavior of liquid contaminants in aquifers and of gases that are injected below the groundwater table for remediation purposes. Considered problems are redistribution of a lens of light nonaqueous phase liquid(LNAPL)on a hor

  11. Accounting for anthropogenic actions in modeling of stream flow at the regional scale

    David, C. H.; Famiglietti, J. S.


    The modeling of the horizontal movement of water from land to coasts at scales ranging from 10^5 km^2 to 10^6 km^2 has benefited from extensive research within the past two decades. In parallel, community technology for gathering/sharing surface water observations and datasets for describing the geography of terrestrial water bodies have recently had groundbreaking advancements. Yet, the fields of computational hydrology and hydroinformatics have barely started to work hand-in-hand, and much research remains to be performed before we can better understand the anthropogenic impact on surface water through combined observations and models. Here, we build on our existing river modeling approach that leverages community state-of-the-art tools such as atmospheric data from the second phase of the North American Land Data Assimilation System (NLDAS2), river networks from the enhanced National Hydrography Dataset (NHDPlus), and observations from the U.S. Geological Survey National Water Information System (NWIS) obtained through CUAHSI webservices. Modifications are made to our integrated observational/modeling system to include treatment for anthropogenic actions such as dams, pumping and divergences in river networks. Initial results of a study focusing on the entire State of California suggest that availability of data describing human alterations on natural river networks associated with proper representation of such actions in our models could help advance hydrology further. Snapshot from an animation of flow in California river networks. The full animation is available at:

  12. Uptake of gaseous formaldehyde onto soil surfaces: a coated-wall flow tube study

    Li, Guo; Su, Hang; Li, Xin; Meusel, Hannah; Kuhn, Uwe; Pöschl, Ulrich; Shao, Min; Cheng, Yafang


    Gaseous formaldehyde (HCHO) is an important intermediate molecule and source of HO2 radicals. However, discrepancies exist between model simulated and observed HCHO concentrations, suggesting missing sources or sinks in the HCHO budget. Multiphase processes on the surface of soil and airborne soil-derived particles have been suggested as an important mechanism for the production/removal of atmospheric trace gases and aerosols. In this work, the uptake of gaseous HCHO on soil surfaces were investigated through coated-wall flow tube experiments with HCHO concentration ranging from 10 to 40 ppbv. The results show that the adsorption of HCHO occurred on soil surfaces, and the uptake coefficient dropped gradually (i.e., by a factor of 5 after 1 hour) as the reactive surface sites were consumed. The HCHO uptake coefficient was found to be affected by the relative humidity (RH), decreasing from (2.4 ± 0.5) × 10-4 at 0% RH to (3.0 ± 0.08) × 10-5 at 70% RH, due to competition of water molecule absorption on the soil surface. A release of HCHO from reacted soil was also detected by applying zero air, suggesting the nature of reversible physical absorption and the existence of an equilibrium at the soil-gas interface. It implies that soil could be either a source or a sink for HCHO, depending on the ambient HCHO concentration. We also develop a Matlab program to calculate the uptake coefficient under laminar flow conditions based on the Cooney-Kim-Davis method.

  13. The effects of forest cover on base flow of streams in the mountainous interior of Puerto Rico, 2010

    Rodriguez-Martínez , Jesús; Santiago, Marilyn


    The U.S. Geological Survey, in cooperation with the Puerto Rico Department of Natural and Environmental Resources, completed a study to determine whether a relation exists between the extent of forest cover and the magnitude of base flow at two sets of paired drainage basins in the highlands of the municipalities of Adjuntas and Utuado within the mountainous interior of Puerto Rico. One set of paired basins includes the Río Guaónica and Río Tanamá, both tributaries of the Río Grande de Arecibo. The other set includes two smaller basins in the drainage basin of the Río Coabey, which is a tributary of the Río Tanamá. The paired basins in each set have similar rainfall patterns, geologic substrate, and aspect; the principal difference identified in the study is the extent of forest cover and related land uses such as the cultivation of shade and sun coffee. Data describing the hydrology, hydrogeology, and streamflow were used in the analysis. The principal objective of the study was to compare base flow per unit area among basins having different areal extents of forest cover and land uses such as shade coffee and sun coffee cultivation. Within the mountainous interior of Puerto Rico, a substantial amount of the annual rainfall (45 to 39 percent in the Rio Guaónica and Rio Tanamá, respectively) can migrate to the subsurface and later emerge as base flow in streams. The magnitude of base flow within the two sets of paired basins varies seasonally. Minimum base flows occur during the annual dry season (generally from January to March), and maximum base flows occur during the wet season (generally from August to October). During the dry season or periods of below-normal rainfall, base flow is either the primary or the sole component of streamflow. Daily mean base flow ranged from 3.2 to 20.5 cubic feet per second (ft3 /s) at the Rio Guaónica Basin, and from 4.2 to 23.0 ft3 /s at the Rio Tanamá Basin. The daily mean base flows during 2010 ranged from 0.28 to 0

  14. Transport of bromide measured by soil coring, suction plates, and lysimeters under transient flow conditions.

    Kasteel, R.; Pütz, Th.; Vereecken, H.


    Lysimeter studies are one step within the registration procedure of pesticides. Flow and transport in these free-draining lysimeters do not reflect the field situation mainly because of the occurence of a zone of local saturation at the lower boundary (seepage face). The objective of this study is to evaluate the impact of flow and transport behaviour of bromide detected with different measuring devices (lysimeters, suction plates, and soil coring) by comparing experimental results with numerical simulations in heterogeneous flow domains. We applied bromide as a small pulse to the bare soil surface (Orthic Luvisol) of the three devices and the displacement of bromide was regurlarly sampled for three years under natural wheather conditions. Based on the mean breakthrough curves we observe experimentally that lysimeters have a lower effective pore-water velocity and exhibit more solute spreading resulting in a larger dispersivity than the suction plates. This can be ascribed to the artefact of the lower boundary. We performed numerical transport simulations in 2-D heterogeneous flow fields (scaling approach) choosing appropriate boundary conditions for the various devices. The simulations allow to follow the temporal evolution of flow and transport processes in the various devices and to gain additional process understanding. We conclude that the model is essentially capable to reproduce the main experimental findings only if we account for the spatial correlation structure of the hydraulic properties, i.e. soil heterogeneity.

  15. An Efficient Multiple-Dimensional Finite Element Solution for Water Flow in Variably Saturated Soils

    QI Xue-bin; ZHANG Xiao-xian; PANG Hong-bin


    Multiple-dimensional water flow in variably saturated soils plays an important role in ecological systems such as irrigation and water uptake by plant roots;its quantitative description is usually based on the Richards' equation.Because of the nonlinearity of the Richards' equation and the complexity of natural soils,most practical simulations rely on numerical solutions with the nonlinearity solved by iterations.The commonly used iterations for solving the nonlinearity are Picard and Newton methods with the former converging at first-order rate and the later at second-order rate.A recent theoretical analysis by the authors,however,revealed that for solving the diffusive flow,the classical Picard method is actually a chord-Newton method,converging at a rate faster than first order;its linear convergence rate is due to the treatment of the gravity term.To improve computational efficiency,a similar chord-Newton method as for solving the diffusive term was proposed to solve the gravity term.Testing examples for one-dimensional flow showed significant improvement.The core of this method is to produce a diagonally dominant matrix in the linear system so as to improve the iteration-toiteration stability and hence the convergence.In this paper,we develop a similar method for multiple-dimensional flow and compare its performance with the classical Picard and Newton methods for water flow in soils characterised by a wide range of van Genuchten parameters.

  16. Flow and transport processes in a macroporous subsurface-drained glacial till soil

    Villholth, Karen G.; Jensen, Karsten Høgh


    -scale concentration gradients, is questioned. Decreasing the domain exchange resulted in an improved model correspondence with the drainage chemograph. The drainage flow pattern was altered between drainage seasons owing to the changes in hydraulic efficiency of surface-vented macropores influenced by the physical......The experimental results from a field-scale tracer experiment in a subsurface-drained glacial till soil were analyzed by the application of a single/dual porosity model (MACRO), optionally accounting for concurrent and interacting flow and transport in the bulk soil porosity as well...... as in the macropores. The model analysis showed that macropore flow is essential in describing the observed transport phenomenon on a short as well as a longer time scale. The diffusive exchange of solute between the matrix and the macropores was very sensitive and critical for the model prediction of the drainage...

  17. The mass flow and proposed management of bisphenol A in selected Norwegian waste streams.

    Arp, Hans Peter H; Morin, Nicolas A O; Hale, Sarah E; Okkenhaug, Gudny; Breivik, Knut; Sparrevik, Magnus


    Current initiatives for waste-handling in a circular economy favor prevention and recycling over incineration or landfilling. However, the impact of such a transition on environmental emissions of contaminants like bisphenol A (BPA) during waste-handling is not fully understood. To address this, a material flow analysis (MFA) was constructed for selected waste categories in Norway, for which the amount recycled is expected to increase in the future; glass, vehicle, electronic, plastic and combustible waste. Combined, 92tons/y of BPA are disposed of via these waste categories in Norway, with 98.5% associated with plastic and electronic waste. During the model year 2011, the MFA showed that BPA in these waste categories was destroyed through incineration (60%), exported for recycling into new products (35%), stored in landfills (4%) or released into the environment (1%). Landfilling led to the greatest environmental emissions (up to 13% of landfilled BPA), and incinerating the smallest (0.001% of incinerated BPA). From modelling different waste management scenarios, the most effective way to reduce BPA emissions are to incinerate BPA-containing waste and avoid landfilling it. A comparison of environmental and human BPA concentrations with CoZMoMAN exposure model estimations suggested that waste emissions are an insignificant regional source. Nevertheless, from monitoring studies, landfill emissions can be a substantial local source of BPA. Regarding the transition to a circular economy, it is clear that disposing of less BPA-containing waste and less landfilling would lead to lower environmental emissions, but several uncertainties remain regarding emissions of BPA during recycling, particularly for paper and plastics. Future research should focus on the fate of BPA, as well as BPA alternatives, in emerging reuse and recycling processes, as part of the transition to a circular economy.

  18. Effect of wavelength of fish-like undulation of a hydrofoil in a free-stream flow



    Fish-like undulating body was proposed as an efficient propulsion system, and various mechanisms of thrust generation in this type of propulsion are found in the literature—separately for undulating and pitching fishes/foil. The present work proposes a unified study for undulating and pitching foil, by varying wavelength l (from 0.8 to 8.0) of a wave traveling backwards over the NACA0012 hydrofoil in a free-stream flow; the larger wavelength is shown to lead to the transition from the undulating motion to pitching motion. The effect ofwavelength of undulation is studied numerically at a Reynolds number Re=4000, maximum amplitude of undulation Amax 0:1 and non-dimensional frequency of undulation St=0:4, using level-set immersedboundary-method based in-house 2D code. The Navier–Stokes equation governing the fluid flow is solved using a fully implicit finite-volume method, while level-set equation governing the movement of the hydrofoil is solved using an explicit finite-difference method. It is presented here that the thrust generation mechanism for the low wavelength case undulating (l=0.8) foil is different from the mechanism for the high wavelength pitching foil. With increasing wavelength, mean thrust coefficient of the undulating foil increases and asymptotes to value for the pure pitching foil. Furthermore, the ratio of maximum thrust coefficient to maximum lateral force coefficient is found to be larger for the smaller wavelength undulating foil as compared with the larger wavelength pitching foil.

  19. Solute flow in extremely stony forest soil: case study in Russian Far East

    Gerke, K.; Gartsman, B.; Bugayets, A.; Korost, D.


    Large impermeable objects like stones can drastically affect numerous soil properties. This contribution is mainly focused on hydrological issues. The original idea of series of field experiments was to visualize and quantify preferential flow paths in extremely stony forest soils on natural hillslopes in Vladivostok region, Russian Federation. This region is known for its intensive rain seasons (monsoon climate). For the purpose mentioned above two large-scale staining tracer experiments were carried out. Up to 200 l of dye solution were uniformly sprinkled over the area of 1 square meter using industrial pressure-calibrated nozzles. Two different tracers were utilized: common staining dye Brilliant Blue FCF and fluorescent dye Uranine. These substances were chosen due to their different staining mechanisms. First common dye solution (100 l) was applied, followed by the same amount of fluorescent dye solution. After full infiltration sequential upslope soil profiles were cut and flow patterns examined using common light for Brilliant Blue FCF and UV light for Uranine. Flow patterns showed unexpected homogeneity, e.g., quite uniform staining profiles and absence of pronounced bundle-like preferential flow paths. Also, no biomat flow (upper layer) was observed. Excavation resulted in quite rough profiles due to large amount of stones; stone positions were reconstructed using shades obtained using digital photos obtained using angled lightening. All infiltration occurred via gaps between stones. Some funneled flow between huge boulders was observed in some cases. Minor differences were observed between two dyes patterns which suggest that infiltration paths were stable. Unfortunately, all observations were not possible for the deepest infiltrations parts because of excavation difficulties increasing with depth (maximum depth reached was around 1.2 m). Undisturbed soil samples were taken from these conducting zones, both stained and unstained portions of soil. However

  20. Evidence that local land use practices influence regional climate, vegetation, and stream flow patterns in adjacent natural areas

    Stohlgren, T.J.; Chase, T.N.; Pielke, R.A.; Kittel, T.G.F.; Baron, J.S.


    We present evidence that land use practices in the plains of Colorado influence regional climate and vegetation in adjacent natural areas in the Rocky Mountains in predictable ways. Mesoscale climate model simulations using the Colorado State University Regional Atmospheric Modelling System (RAMS) projected that modifications to natural vegetation in the plains, primarily due to agriculture and urbanization, could produce lower summer temperatures in the mountains. We corroborate the RAMS simulations with three independent sets of data: (i) climate records from 16 weather stations, which showed significant trends of decreasing July temperatures in recent decades; (ii) the distribution of seedlings of five dominant conifer species in Rocky Mountain National Park, Colorado, which suggested that cooler, wetter conditions occurred over roughly the same time period; and (iii) increased stream flow, normalized for changes in precipitation, during the summer months in four river basins, which also indicates cooler summer temperatures and lower transpiration at landscape scales. Combined, the mesoscale atmospheric/land-surface model, short-term in regional temperatures, forest distribution changes, and hydrology data indicate that the effects of land use practices on regional climate may overshadow larger-scale temperature changes commonly associated with observed increases in CO2 and other greenhouse gases.

  1. Determining solute inputs to soil and stream waters in a seasonally snow-covered mountain catchment in northern New Mexico using Ge/Si and 87Sr/86Sr ratios

    Porter, C. M.; McIntosh, J. C.; Derry, L. A.; Meixner, T.; Chorover, J.; Rasmussen, C.; Brooks, P. D.; Perdrial, J. N.


    The critical zone is the environment near the Earth's surface in which biological, chemical, and physical processes interact and contribute to the evolution and structure of life on Earth. Mineral dissolution is an important process in the critical zone that supplies essential nutrients, to the biotic foundation of ecosystems. Stream chemical composition reflects the supply through mineral weathering and the loss of these elements through hydrologic transport. This study aims to determine the influence of mineral weathering on stream and soil water composition in a seasonally snow-covered headwater catchment in the Jemez Mountains in northern New Mexico by using a multi-tracer approach including major cations, strontium isotopes, germanium (Ge)/silica (Si) ratios and trace metals. Potential solute sources to stream waters include snowmelt, atmospheric wet and dry deposition, groundwaters and soil waters influenced by mineral weathering. Preliminary base cation, dissolved inorganic carbon (DIC), and dissolved organic carbon (DOC) results show that groundwater dominates stream water composition except during snowmelt in April and May. Furthermore, stream waters are enriched in base cations compared to snowmelt discharge and shallow soil waters suggesting contributions of solutes from mineral weathering along deeper subsurface flowpaths. Dilution trends of base cation concentrations are not observed during snowmelt, however high DOC and low DIC concentrations are present in stream waters indicating shallow soil flushing. Soil solid phase chemistry data shows soils are depleted in Ca, relative to Na, and K whereas stream waters are enriched in Ca, relative to Na, and K, which may be indicative of plagioclase or calcite weathering. Soils deeper in the soil profile are depleted in Ge relative to Si, whereas shallow soils are enriched in Ge. Therefore we hypothesize that shallow soil flushing during snowmelt periods will lead to elevated Ge/Si ratios in stream waters. In

  2. Influence of the contaminated wastes/soils on the geochemical characteristics of the Bodelhão stream waters and sediments from Panasqueira mine area, Portugal

    Abreu, Maria Manuela; Godinho, Berta; Magalhães, Maria Clara F.; Anjos, Carla; Santos, Erika


    Panasqueira is a famous Portuguese tin-tungsten mine operating more or less continuously since the end of the nineteenth century. This mine is located in the Central Iberian Zone, northwest of Castelo Branco, about 35 km from Fundão, being the greatest producer of tungsten in Europe. Panasqueira mine also produces copper and tin. The ore exploitation has caused huge local visual and chemical impact from the large waste tailings, together with water drainage from mine galleries, seepage and effluents from water plant treatment. The objective of this work was to evaluate the influence of the contaminated wastes and soils on the water and sediments characteristics of the Bodelhão stream. This stream crosses the mine area at the bottom of the main tailings, receiving sediments, seepage and drainage waters from wastes and/or soils developed on the waste materials which cover the host rocks (schists), and also from the water treatment plant. Waste materials contain different levels of hazardous chemical elements depending on their age and degree of weathering (mg/kg - As: 466-632; Cd: 2.6-4.2; Cu: 264-457; Zn: 340-456; W: 40-1310). Soils developed on old wastes (60-80 years old) are mainly silty loam, acidic (except one soil (pH 8.2) developed on waste materials covered by leakage mud from a pipe conducting effluent to a pond), with relatively high concentration of organic carbon (median 48.6 g/kg). The majority of soils are heavily contaminated in As (158-7790 mg/kg), Cd (0.6-138 mg/kg), Cu (51-4081 mg/kg), W (19-1450 mg/kg), and Zn (142-12300 mg/kg). The fraction of these elements extracted with DTPA solution, relatively to total concentration, varies from low to As (bank sediments (g/kg, As: 5.56-44.0; Cu: 1.99- >10; Zn: 1.29-14.1; S: 7.2-66.9; W: 1.04-6.32, and Cd: 11.4-138 mg/kg) when compared with the same elements in soils, indicate high dispersion of the chemical elements through waters both in solution and particulate material. Bed and river banks are

  3. Low-flow characteristics of streams under natural and diversion conditions, Waipiʻo Valley, Island of Hawaiʻi, Hawaiʻi

    Fontaine, Richard A.


    Over the past 100 years, natural streamflow in Waipiʻo Valley has been reduced by the transfer of water out of the valley by Upper and Lower Hāmākua Ditches. The physical condition and diversion practices along the two ditch systems have varied widely over the years, and as a result, so have their effects on natural streamflow in Waipiʻo Valley. Recent renovation and improvements to Lower Hāmākua Ditch system, along with proposals for its future operation and water-diversion strategies, have unknown implications. The purpose of this report is to quantify the availability of streamflow and to determine the effects of current and proposed diversion strategies on the low-flow hydrology in Waipiʻo Valley. In this report, the low-flow hydrology of Waipiʻo Valley is described in terms of flow-duration statistics. Flow-duration statistics were computed for three locations in the Waipiʻo Valley study area where long-term surface-water gaging stations have been operated. Using a variety of streamflow record-extension techniques, flow-duration statistics were estimated at an additional 13 locations where only few historical data are available or where discharge measurements were made as part of this study. Flow-duration statistics were computed to reflect natural conditions, current (2000-2005) diversion conditions, and proposed future diversion conditions at the 16 locations. At the downstream limit of the study area, on Wailoa Stream at an altitude of 190 feet, a baseline for evaluating the availability of streamflow is provided by computed flow-duration statistics that are representative of natural, no-diversion conditions. At the Wailoa gaging station, 95- and 50-percentile discharges under natural conditions were determined to be 86 and 112 cubic feet per second, respectively. Under 1965-1969 diversion conditions, natural 95- and 50-percentile discharges were reduced by 52 and 53 percent, to 41 and 53 cubic feet per second, respectively. Under current (2000

  4. Impacts of Stream Flow and Climate Variability on Native and Invasive Woody Species in a Riparian Ecosystem of a Semi-Arid Region of the Great Plains, USA

    Skolaut, K.; Awada, T.; Cherubini, P.; Schapaugh, A.


    Riparian ecosystems support diverse plant communities that exert direct and indirect biological, physical and chemical influence on, and are influenced by, adjacent water through both above and below-ground interactions. Historically, riparian areas of the northern Great Plains, US have been dominated by the native Populus deltoides (eastern cottonwood). This species relies on regular floods for regeneration and groundwater access for success. Over the past sixty years, changes in flow management and agricultural practices, coupled with climate variability and drought have altered stream flow and caused a dramatic decline in stream water yields and levels of groundwater. These and other biotic and biotic factors have promoted the expansion of the upland native woody species Juniperus virginiana (eastern redcedar), and the invasion of the non-native (introduced) Elaeagnus angustifolia (Russian olive) into riparian ecosystems. This invasion has further altered the water balance in the system and exasperated the problem of water scarcity with negative feedback on ecosystem services and growth of native woody species. The ability of P. deltoides to re-establish and grow is of concern for natural resource managers. Tree ring analysis of annual growth rates were used to determine 1) the responses P. deltoides and invasive J. virginiana and E. angustifulia to climate variability and stream flow regulation, and 2) the impacts of the two invasive species on the growth of native P. deltoides. Results show a dependency of growth for P. deltoides on the previous year summer temperature, and a less significant correlation to annual stream flow. J. virginiana showed the highest correlation to annual stream flow, as well as some dependency on the previous growing season precipitation. While the growth of both P. deltoides and J. virginiana displayed greater dependence on climatic factors, E. angustifolia displayed the lowest mean basal area growth and deviation from the growth. E

  5. Chemical composition of overland flow produced on soils covered with vegetative ash

    M.B. Bodí


    Full Text Available The objective of this study was to ascertain the differences between the soluble elements of ash obtained under laboratory conditions and the dissolved in overland flow from soils covered with a layer of ash. The overland flow was obtained during series of rainfall simulations over soils covered with two different types of ash. This study indicates that the soluble elements released from ash can modify water quality increasing its pH, electrical conductivity and especially cation content. The nutrients solubilised are not necessarily the same as the elemental composition of ash itself. Runoff composition depends on the volume of water produced, on the solubility of the ash components and on the chemical interactions with water from rainfall and soil. After the first intense rain event, most of the elements are solubilised and lixiviated or washed out, however, some of them may increase in the runoff or soil water some weeks later due to chemical interactions with water from rainfall and soil nutrients.

  6. Modeling the release of Escherichia coli from soil into overland flow under raindrop impact

    Wang, C.; Parlange, J.-Y.; Rasmussen, E. W.; Wang, X.; Chen, M.; Dahlke, H. E.; Walter, M. T.


    Pathogen transport through the environment is complicated, involving a variety of physical, chemical, and biological processes. This study considered the transfer of microorganisms from soil into overland flow under rain-splash conditions. Although microorganisms are colloidal particles, they are commonly quantified as colony-forming units (CFUs) per volume rather than as a mass or number of particles per volume, which poses a modeling challenge. However, for very small particles that essentially remain suspended after being ejected into ponded water and for which diffusion can be neglected, the Gao model, originally derived for solute transfer from soil, describes particle transfer into suspension and is identical to the Hairsine-Rose particle erosion model for this special application. Small-scale rainfall experiments were conducted in which an Escherichia coli (E. coli) suspension was mixed with a simple soil (9:1 sand-to-clay mass ratio). The model fit the experimental E. coli data. Although re-conceptualizing the Gao solute model as a particle suspension model was convenient for accommodating the unfortunate units of CFU ml-1, the Hairsine-Rose model is insensitive to assumptions about E. coli per CFU as long as the assumed initial mass concentration of E. coli is very small compared to that of the soil particle classes. Although they undoubtedly actively interact with their environment, this study shows that transport of microorganisms from soil into overland storm flows can be reasonably modeled using the same principles that have been applied to small mineral particles in previous studies.

  7. Soil and Waste Matrix Affects Spatial Heterogeneity of Bacteria Filtration during Unsaturated Flow

    Adrian Unc


    Full Text Available Discontinuous flows resulting from discrete natural rain events induce temporal and spatial variability in the transport of bacteria from organic waste through soils in which the degree of saturation varies. Transport and continuity of associated pathways are dependent on structure and stability of the soil under conditions of variable moisture and ionic strength of the soil solution. Lysimeters containing undisturbed monoliths of clay, clay loam or sandy loam soils were used to investigate transport and pathway continuity for bacteria and hydrophobic fluorescent microspheres. Biosolids, to which the microspheres were added, were surface applied and followed by serial irrigation events. Microspheres, Escherichia coli, Enterococcus spp., Salmonella spp. and Clostridium perfringens were enumerated in drainage collected from 64 distinct collection areas through funnels installed in a grid pattern at the lower boundary of the monoliths. Bacteria-dependent filtration coefficients along pathways of increasing water flux were independent of flow volume, suggesting: (1 tracer or colloid dependent retention; and (2 transport depended on the total volume of contiguous pores accessible for bacteria transport. Management decisions, in this case resulting from the form of organic waste, induced changes in tortuosity and continuity of pores and modified the effective capacity of soil to retain bacteria. Surface application of liquid municipal biosolids had a negative impact on transport pathway continuity, relative to the solid municipal biosolids, enhancing retention under less favourable electrostatic conditions consistent with an initial increase in straining within inactive pores and subsequent by limited re-suspension from reactivated pores.

  8. Identifying Erosional Hotspots in Streams Along the North Shore of Lake Superior, Minnesota using High-Resolution Elevation and Soils Data

    Wick, Molly J.

    Many streams on the North Shore of Lake Superior, Minnesota, USA, are impaired for turbidity driven by excess fine sediment loading. The goal of this project was to develop a GIS-based model using new, openly-available, high-resolution remote datasets to predict erosional hotspots at a reach scale, based on three study watersheds: Amity Creek, the Talmadge River, and the French River. The ability to identify erosional hotspots, or locations that are highly susceptible to erosion, using remote data would be helpful for watershed managers in implementing practices to reduce turbidity in these streams. Erosion in streams is a balance between driving forces, largely controlled by topography; and resisting forces, controlled by the materials that make up a channel's bed and banks. New high-resolution topography and soils datasets for the North Shore provide the opportunity to extract these driving and resisting forces from remote datasets and possibly predict erosion potential and identify erosional hotspots. We used 3-meter LiDAR-derived DEMs to calculate a stream power-based erosion index, to identify stream reaches with high radius of curvature, and to identify stream reaches proximal to high bluffs. We used the Soil Survey Geographic (SSURGO) Database to investigate changes in erodibility along the channel. Because bedrock exposure significantly limits erodibility, we investigated bedrock exposure using bedrock outcrop maps made available by the Minnesota Geological Survey (MGS, Hobbs, 2002; Hobbs, 2009), and by using a feature extraction tool to remotely map bedrock exposure using high-resolution air photos and LiDAR data. Predictions based on remote data were compared with two datasets. Bank Erosion Hazard Index surveys, which are surveys designed to evaluate erosion susceptibility of banks, were collected along the three streams. In addition, a 500-year flood event during our field season gave us the opportunity to collect erosion data after a major event and

  9. Soil water retention, air flow and pore structure characteristics after corn cob biochar application to a tropical sandy loam

    Amoakwah, Emmanuel; Frimpong, Kwame Agyei; Okae-Anti, D


    Soil structure is a key soil physical property that affects soil water balance, gas transport, plant growth and development, and ultimately plant yield. Biochar has received global recognition as a soil amendment with the potential to ameliorate the structure of degraded soils. We investigated how...... corn cob biochar contributed to changes in soil water retention, air flow by convection and diffusion, and derived soil structure indices in a tropical sandy loam. Intact soil cores were taken from a field experiment that had plots without biochar (CT), and plots each with 10 t ha− 1 (BC-10), 20 t ha...... to significant increase in soil water retention compared to the CT and BC-10 as a result of increased microporosity (pores biochar had minimal impact. No significant influence of biochar was observed for ka and Dp/D0 for the BC treatments compared to the CT despite...

  10. Soil erosion and sediment yield and their relationships with vegetation cover in upper stream of the Yellow River

    Ouyang, W.; Hao, F.; Skidmore, A.K.; Toxopeus, A.G.


    Soil erosion is a significant concern when considering regional environmental protection, especially in the Yellow River Basin in China. This study evaluated the temporal-spatial interaction of land cover status with soil erosion characteristics in the Longliu Catchment of China, using the Soil and

  11. Asymmetric Flow Field-Flow Fractionation of Manufactured Silver Nanoparticles in Soil Water Extracts

    Koopmans, G.F.; Hiemstra, T.; Molleman, B.; Regelink, I.C.; Comans, R.N.J.


    Manufactured silver nanoparticles (AgNP) are among the most widely used nanoparticles in consumer products and their unintended release into the environment has become a serious concern. For a meaningful assessment of the risks of AgNP in soils, their concentration and particle-size-distribution in

  12. Analytical results and sample locations of reanalyzed NURE stream-sediment and soil samples for the Humboldt River basin mineral-environmental assessment, northern Nevada

    Folger, H. W.


    The U.S. Geological Survey (USGS), in cooperation with the Bureau of Land Management (BLM), began a study in 1996 to describe to the geochemistry of the Humboldt River Basin. The principal sample media evaluated are stream-sediment and soil samples retrieved from the National Uranium Resource Evaluation (NURE) archives located in Denver, Colorado. Samples were retrieved from the Wells, McDermitt, Vya, Lovelock, Winnemucca, Elko, Ely, Millett, Reno, and Tonopah 1? x 2? quadrangles in northern Nevada. The data are appropriate for large-scale reconnaissance resource evaluations and landscape geochemical-geoenvironmental evaluations. The analytical results are presented in this report.

  13. Influence of geology, regolith and soil on fluid flow pathways in an upland catchment in central NSW, Australia

    Bernardi, Tony


    Influence of geology, regolith and soil on fluid flow pathways in an upland catchment in central NSW, Australia. Tony Bernardi and Leah Moore Dryland Salinity Hazard Mitigation Program (DSHMP), University of Canberra, ACT 2601, AUSTRALIA The diversity of salt expression in central NSW has defied classification because salt expression, mobilisation and transport is highly variable and is typically site specific. Hydrological models are extensively used to simulate possible outcomes for a range of land use changes to mitigate the mobilisation and transport of salt into the streams or across the land surface. The ability of these models to mimic reality can be variable thereby reducing the confidence in the models outputs and uptake of strategic management changes by the community. This study focuses on a 250 ha semi-arid sub-catchment of Little River catchment in central west NSW in the Murray-Darling Basin, Australia. We propose that an understanding the structure of the landforms and configuration of rock, regolith and soil materials at the study site influences fluid flow pathways in the landscape and can be related to observed variations in the chemical composition and salinity of surface and aquifer water. Preliminary geological mapping of the site identified the dominant rock type as a pink and grey dacite and in localised mid-slope areas, a coarsely crystalline biotite-phyric granodiorite. Samples were taken at regular intervals from natural exposures in eroded stream banks and in excavations made during the installation of neutron moisture meter tubes. In order to establish mineral weathering pathways, samples were taken from the relatively unweathered core to the outer weathered 'onion skins' of corestones on both substrates, and then up through the regolith profile, including the soil zone, to the land surface. X-ray diffraction (XRD) analysis and X-ray fluorescence (XRF) was conducted on the rock and soil/saprock samples. Electromagnetic induction (EMI

  14. A Comparison of Molecular and Isotopic Chemistry of Overland Flow DOM and yPOM to Soil Sources From a Small Mid-western Agricultural Basin

    Crooker, K.; Filley, T. R.; Six, J.; Frey, J.


    In agricultural watersheds, the mobilization of terrestrial organic matter into yaquatic environments has been linked to increased primary productivity and ymicrobial activity in the tributaries of large-order streams and rivers. The yincrease in primary productivity and microbial activity results in downstream ynutrient export which can increase decomposition rates, turbidity, release of ycarbon dioxide to the atmosphere, and reduce the dissolved oxygen levels that yaquatic fauna rely upon to survive. The intensity and frequency of storms is a ycritical factor in determining the mass and chemical character of organic matter ymobilized as overland flow from agricultural watersheds. We will present results yfrom biogeochemical characterization of size fractionated aquatic and soil yorganic matter collected during storm events from a 2.5 Km2 drainage area in ycentral Indiana, part of the U.S. Geological Survey National Water-Quality yAssessment. Molecular and isotopic techniques were applied to size fractions of ysource surface soils and to the resultant dissolved, colloidal, and particulate yaquatic fractions isolated by cross-flow ultra-filtration at the overland flow site and ydown stream. Alkaline CuO oxidation of the size fractions was performed to yrelease lignin and aliphatic biopolymer (cutin and suberin) components. yPreliminary results indicate that dissolved organic components released during ythe storm are more degraded than particulate and colloidal materials. Compound yspecific and bulk carbon isotope analyses of the fractions will help us discern if yselective mobilization and decomposition is a factor in controlling the organic ymatter discharge volume from either the added C3 soybean or C4 corn in this ycorn/soybean rotation system.y

  15. Variation of δ18O and δD in precipitation and stream waters across the Kashmir Himalaya (India) to distinguish and estimate the seasonal sources of stream flow

    Jeelani, Gh.; Saravana Kumar, U.; Kumar, Bhishm


    SummaryThe spatial and temporal distribution of δ18O and δD measurements of precipitation and stream waters were used to distinguish various sources and components of stream flow and to estimate their residence times in snow dominated mountainous catchments of Kashmir Himalaya. A marked spatial and seasonal variability of stable isotopes of oxygen and hydrogen was observed in precipitation with δ18O and δD varied from -12.98‰ to -0.58‰ and -74.5‰ to -11.1‰, respectively during the period from November 2007 to January 2009. The seasonal changes in stable isotopes of precipitation with depleted and enriched 18O and 2H in January/March/May and July/September/November, respectively at each site are attributed to the seasonal changes in ambient temperature, precipitation, source of moisture and airmass trajectory. The mean altitude effect of -0.23‰ and -1.2‰ per 100 m change in elevation for δ18O and δD, respectively, was observed based on amount weighted mean precipitation isotopic composition data. Unlike precipitation, less variability of stable isotopes of streams was found with δ18O and δD ranging from -11.56‰ to -6.26‰ and -65.4‰ to -36.4‰, respectively, the depleted values being observed in the headwaters of the streams/tributaries and enriched values at lower elevations of the watersheds. The LMWL established for the Kashmir Himalayas, based on amount weighted monthly samples is δD = 7.59 (± 0.32) × δ18O + 11.79 (± 2.07) (r2 = 0.96) with lower slope and intercept than GMWL, is very close to the LMWL for the western Himalayas. The seasonal regression lines suggest the effect of evaporation with lower slopes and intercepts except in winter. The results suggest that the winter precipitation (snow) dominantly contributes the annual stream flow with average snowmelt contribution of about 29% in early spring, 66% in late spring, 61% in summer while the baseflow contribution is found in the order of 40% in autumn season. The mean stream

  16. Investigation of the Effects of Anisotropic Flow of Pore Water and Multilayered Soils on Three-Dimensional Consolidation Characteristics

    Arpan Laskar


    Full Text Available Many practical engineering problems are seriously different from the assumptions which are considered for one-dimensional consolidation test and need to concentrate on three-dimensional consolidation of soil under different boundary conditions. In this study three-dimensional consolidation tests are performed with four different anisotropic flow conditions of pore water and fifteen different combinations of horizontal layered soils. Twelve different three-dimensional consolidation tests are also performed with different soils, surrounded by anisotropic vertical soil layers on two opposite sides. From these studies, it is observed that the anisotropic flow of pore water does not have any effect on initial and final surface settlement of soil but has a significant effect during the consolidation process. The anisotropic flow of pore water during the consolidation process has an immense effect on the coefficient of consolidation. Horizontal layered soil has a great effect on both surface settlement and the rate of settlement. Vertical soil layers on two opposite sides of consolidative soil have an immense effect on the horizontal movements of consolidating soil, finally affecting the resultant vertical settlement of soil. Vertical anisotropic surrounding soil layers also have an effect on the rate of consolidation settlement.

  17. Scaling and Pedotransfer in Numerical Simulations of Flow and Transport in Soils

    Pachepsky, Y. A.; Yakirevich, A.; Guber, A.; Gish, T.; Cady, R.; Nicholson, T. J.


    Flow and transport parameters in numerical simulations need to be defined at the support volume of computational cells. This volume can be substantially larger than the support volume in laboratory of field measurements of those parameters. Parameter estimates obtained from measured values with pedotransfer functions are also defined at the measurement rather than simulation cell support scale. The scale dependence of flow and transport parameters essentially precludes the direct use of measured or pedotransfer estimated parameter values in numerical simulations. The hypothesis of this work was that a support volume-based scaling law could be introduced that could convert pedotransfer-estimated saturated hydraulic conductivity values into values to be used over grid cells for finite element-based simulations of water flow and tracer transport in variable saturated soils. A four month-long experiment was conducted at the USDA-ARS experimental site where tracer was applied with a pulse of irrigation water and its transport in groundwater and variably saturated shallow soils was monitored in three rows of wells on daily basis. The complementary weather data collection and runoff volume measurements were performed. The HYDRUS-3D software was used to set and calibrate the Richards model for flow simulations and the convective-dispersive equation for transport simulations. Saturated hydraulic conductivity values were estimated with class pedotransfer functions derived from the USDA database containing results of about 1000 measurements in soils of different textures and bulk density. A power law scaling law for the saturated hydraulic conductivity was derived from literature data and was applied at the OPE3 site. Using the scaled saturated hydraulic conductivity values resulted in the accuracy of simulations that was similar to the accuracy of the calibrated model results. Scaling of pedotransfer-estimated saturated hydraulic conductivities can provide reasonable

  18. Surface-water quantity and quality, aquatic biology, stream geomorphology, and groundwater-flow simulation for National Guard Training Center at Fort Indiantown Gap, Pennsylvania, 2002-05

    Langland, Michael J.; Cinotto, Peter J.; Chichester, Douglas C.; Bilger, Michael D.; Brightbill, Robin A.


    Base-line and long-term monitoring of water resources of the National Guard Training Center at Fort Indiantown Gap in south-central Pennsylvania began in 2002. Results of continuous monitoring of streamflow and turbidity and monthly and stormflow water-quality samples from two continuous-record long-term stream sites, periodic collection of water-quality samples from five miscellaneous stream sites, and annual collection of biological data from 2002 to 2005 at 27 sites are discussed. In addition, results from a stream-geomorphic analysis and classification and a regional groundwater-flow model are included. Streamflow at the facility was above normal for the 2003 through 2005 water years and extremely high-flow events occurred in 2003 and in 2004. Water-quality samples were analyzed for nutrients, sediments, metals, major ions, pesticides, volatile and semi-volatile organic compounds, and explosives. Results indicated no exceedances for any constituent (except iron) above the primary and secondary drinking-water standards or health-advisory levels set by the U.S. Environmental Protection Agency. Iron concentrations were naturally elevated in the groundwater within the watershed because of bedrock lithology. The majority of the constituents were at or below the method detection limit. Sediment loads were dominated by precipitation due to the remnants of Hurricane Ivan in September 2004. More than 60 percent of the sediment load measured during the entire study was transported past the streamgage in just 2 days during that event. Habitat and aquatic-invertebrate data were collected in the summers of 2002-05, and fish data were collected in 2004. Although 2002 was a drought year, 2003-05 were above-normal flow years. Results indicated a wide diversity in invertebrates, good numbers of taxa (distinct organisms), and on the basis of a combination of metrics, the majority of the 27 sites indicated no or slight impairment. Fish-metric data from 25 sites indicated results

  19. Water temperature, dissolved oxygen, flow, and shade measurements in the three stream sections of the Golden Trout Wilderness

    Kathleen R. Matthews


    To determine the current range of water temperatures in the streams inhabited by California golden trout, Oncorhynchus mykiss aguabonita, I deployed and monitored water temperature recording probes from 2008 through 2013 in three meadows in the Golden Trout Wilderness (GTW). Ninety probes were placed in three meadow streams: Mulkey Creek in Mulkey...

  20. New methods for modeling stream temperature using high resolution LiDAR, solar radiation analysis and flow accumulated values

    In-stream temperature directly effects a variety of biotic organisms, communities and processes. Changes in stream temperature can render formally suitable habitat unsuitable for aquatic organisms, particularly native cold water species that are not able to adjust. In order to an...

  1. Modeling fecal bacteria transport and retention in agricultural and urban soils under saturated and unsaturated flow conditions.

    Balkhair, Khaled S


    Pathogenic bacteria, that enter surface water bodies and groundwater systems through unmanaged wastewater land application, pose a great risk to human health. In this study, six soil column experiments were conducted to simulate the vulnerability of agricultural and urban field soils for fecal bacteria transport and retention under saturated and unsaturated flow conditions. HYDRUS-1D kinetic attachment and kinetic attachment-detachment models were used to simulate the breakthrough curves of the experimental data by fitting model parameters. Results indicated significant differences in the retention and drainage of bacteria between saturated and unsaturated flow condition in the two studied soils. Flow under unsaturated condition retained more bacteria than the saturated flow case. The high bacteria retention in the urban soil compared to agricultural soil is ascribed not only to the dynamic attachment and sorption mechanisms but also to the greater surface area of fine particles and low flow rate. All models simulated experimental data satisfactorily under saturated flow conditions; however, under variably saturated flow, the peak concentrations were overestimated by the attachment-detachment model and underestimated by the attachment model with blocking. The good match between observed data and simulated concentrations by the attachment model which was supported by the Akaike information criterion (AIC) for model selection indicates that the first-order attachment coefficient was sufficient to represent the quantitative and temporal distribution of bacteria in the soil column. On the other hand, the total mass balance of the drained and retained bacteria in all transport experiments was in the range of values commonly found in the literature. Regardless of flow conditions and soil texture, most of the bacteria were retained in the top 12 cm of the soil column. The approaches and the models used in this study have proven to be a good tool for simulating fecal

  2. Multi-scale measurements and modeling of denitrification in streams with varying flow and nitrate concentration in the upper Mississippi River basin, USA

    Bohlke, Johnkarl F.; Antweiler, Ronald C.; Harvey, Judson W.; Smith, Richard L.; Voytek, Mary A.; Laursen, A.; Smith, L.K.


    Denitrification is an important net sink for NO3 - in streams, but direct measurements are limited and in situ controlling factors are not well known. We measured denitrification at multiple scales over a range of flow conditions and NO3 - concentrations in streams draining agricultural land in the upper Mississippi River basin. Comparisons of reach-scale measurements (in-stream mass transport and tracer tests) with local-scale in situ measurements (pore-water profiles, benthic chambers) and laboratory data (sediment core microcosms) gave evidence for heterogeneity in factors affecting benthic denitrification both temporally (e.g., seasonal variation in NO3 - concentrations and loads, flood-related disruption and re-growth of benthic communities and organic deposits) and spatially (e.g., local stream morphology and sediment characteristics). When expressed as vertical denitrification flux per unit area of streambed (U denit, in µmol N m-2 h-1), results of different methods for a given set of conditions commonly were in agreement within a factor of 2–3. At approximately constant temperature (~20 ± 4°C) and with minimal benthic disturbance, our aggregated data indicated an overall positive relation between U denit (~0–4,000 µmol N m-2 h-1) and stream NO3 - concentration (~20–1,100 µmol L-1) representing seasonal variation from spring high flow (high NO3 -) to late summer low flow (low NO3 -). The temporal dependence of U denit on NO3 - was less than first-order and could be described about equally well with power-law or saturation equations (e.g., for the unweighted dataset, U denit ˜26 * [NO3 -]0.44 or U denit ˜640 * [NO3 -]/[180 + NO3 -]; for a partially weighted dataset, U denit ˜14 * [NO3 -]0.54 or U denit ˜700 * [NO3 -]/[320 + NO3 -]). Similar parameters were derived from a recent spatial comparison of stream denitrification extending to lower NO3 - concentrations (LINX2), and from the combined dataset from both studies over 3 orders of magnitude

  3. Effects of Soil Compaction and Organic Carbon Content on Preferential Flow in Loamy Field Soils

    Soares, Antonio; Moldrup, Per; Vendelboe, Anders Lindblad


    Preferential flow and transport through macropores affects plant water use efficiency and enhances leaching of agrochemicals and the transport of colloids, thereby increasing the risk for contamination of groundwater resources. As part of the Danish Pesticide Leaching Assessment Program this study...

  4. Processes of Salt Transport in Disturbed Streams

    Chitrakar, S.; Miller, S. N.; Caffrey, P. A.; Stern, J.


    The extraction of coal bed methane natural gas involves removal of large amount of ground/Coal Bed Methane (CBM) water which is commonly discharged to surface-water drainages or constructed reservoirs. The extraction of large volume of water and its disposal on soil surface not only lowers the water table but also potentially accelerate soil erosions, contaminate surface water resources, and alter the natural flows. Due to the difference in quality and quantity between the surface discharge and disposed CBM water, this management strategy potentially poses threats to quality of surface water and soil. CBM discharge water typically contains high concentrations of sodium and low concentrations of calcium and magnesium, resulting in high sodium adsorption ratio (SAR). Similarly, it also contains high concentration of other ions which could results in increasing salt concentrations. Our study area is in the Atlantic Rim development area of the Muddy Creek, SE of Wyoming, a tributary to Colorado River, where significant development of CBM wells is ongoing. Since Muddy Creek is part of the Upper Colorado River, the greatest concern is its potential to contribute to surface water quality (primarily salinity) impairment downstream. However, very few studies have made efforts to assess the water quality in this particular region. The alteration of stream water quality in this region is still not fully understood if it due to CBM water discharge or via soil/water interactions, erosion, and sediment transport. Efforts are being made to identify crucial water quality parameters such as SAR and EC along with the quantification of solute/salt loadings at both CBM discharge fed streams and natural streams at different seasons to distinguish effect of CBM discharge on water quality. We have been continuously monitoring water quality on monthly basis and discharge measurement on daily basis at sampling sites that are placed to discriminate CBM fed streams and natural streams. The

  5. Application of chemical oxidation to remediate HCH-contaminated soil under batch and flow through conditions.

    Usman, Muhammad; Tascone, Oriane; Rybnikova, Victoria; Faure, Pierre; Hanna, Khalil


    This is the first study describing the chemical oxidation of hexachlorocyclohexanes (HCHs) in contaminated soil under water saturated and unsaturated flow through conditions. Soil contaminated with β-HCH (45 mg kg(-1)) and γ-HCH (lindane, 25 mg kg(-1)) was sampled from former lindane waste storage site. Efficiency of following treatments was tested at circumneutral pH: H2O2 alone, H2O2/Fe(II), Na2S2O8 alone, Na2S2O8/Fe(II), and KMnO4. Experimental conditions (oxidant dose, liquid/solid ratio, and soil granulometry) were first optimized in batch experiments. Obtained results revealed that increasing dose of H2O2 improved the oxidation efficiency while in Na2S2O8 system, maximum HCHs were removed at 300 mM. However, oxidation efficiency was slightly improved by Fe(II)-activation. Increasing the solid/liquid ratio decreased HCH removal in soil samples crushed to 500 μm while an opposite trend was observed for 2-mm samples. Dynamic column experiments showed that oxidation efficiency followed the order KMnO4 > Na2S2O8/Fe(II) > Na2S2O8 whatever the flow condition, whereas the removal extent declined at higher flow rate (e.g., ~50% by KMnO4 at 0.5 mL/min as compared to ~30% at 2 mL/min). Both HCH removal and oxidant decomposition extents were found higher in saturated columns than the unsaturated ones. While no significant change in relative abundance of soil mineral constituents was observed before and after chemical oxidation, more than 60% of extractable organic matter was lost after chemical oxidation, thereby underscoring the non-selective behavior of chemical oxidation in soil. Due to the complexity of soil system, chemical oxidation has rarely been reported under flow through conditions, and therefore our findings will have promising implications in developing remediation techniques under dynamic conditions closer to field applications.

  6. Burning management in the tallgrass prairie affects root decomposition, soil food web structure and carbon flow

    Shaw, E. A.; Denef, K.; Milano de Tomasel, C.; Cotrufo, M. F.; Wall, D. H.


    Root litter decomposition is a major component of carbon (C) cycling in grasslands, where it provides energy and nutrients for soil microbes and fauna. This is especially important in grasslands where fire is a common management practice and removes aboveground litter accumulation. In this study, we investigated whether fire affects root decomposition and C flow through the belowground food web. In a greenhouse experiment, we applied 13C-enriched big bluestem (Andropogon gerardii) root litter to intact tallgrass prairie soil cores collected from annually burned (AB) and infrequently burned (IB) treatments at the Konza Prairie Long Term Ecological Research (LTER) site. Incorporation of 13C into microbial phospholipid fatty acids and nematode trophic groups was measured on six occasions during a 180-day decomposition study to determine how C was translocated through the soil food web. Results showed significantly different soil communities between treatments and higher microbial abundance for IB. Root decomposition occurred rapidly and was significantly greater for AB. Microbes and their nematode consumers immediately assimilated root litter C in both treatments. Root litter C was preferentially incorporated in a few groups of microbes and nematodes, but depended on burn treatment: fungi, Gram-negative bacteria, Gram-positive bacteria, and fungivore nematodes for AB and only omnivore nematodes for IB. The overall microbial pool of root litter-derived C significantly increased over time but was not significantly different between burn treatments. The nematode pool of root litter-derived C also significantly increased over time, and was significantly higher for the AB treatment at 35 and 90 days after litter addition. In conclusion, the C flow from root litter to microbes to nematodes is not only measurable, but significant, indicating that higher nematode trophic levels are critical components of C flow during root decomposition which, in turn, is significantly

  7. Two-dimensional prognostic experiments for fast-flowing ice streams from the Academy of Sciences Ice Cap: future modeled histories obtained for the reference surface mass balance

    Y. V. Konovalov


    Full Text Available The prognostic experiments for fast-flowing ice streams on the southern side of the Academy of Sciences Ice Cap in the Komsomolets Island, Severnaya Zemlya archipelago, are implemented in this study. These experiments are based on inversions of basal friction coefficients using a two-dimensional flow-line thermo-coupled model and the Tikhonov's regularization method. The modeled ice temperature distributions in the cross-sections were obtained using the ice surface temperature histories that were inverted previously from the borehole temperature profiles derived at the Academy of Sciences Ice Cap. Input data included InSAR ice surface velocities, ice surface elevations, and ice thicknesses obtained from airborne measurements and the surface mass balance, were adopted from the prior investigations for the implementation of both the forward and inverse problems. The prognostic experiments reveal that both ice mass and ice stream extents decline for the reference time-independent surface mass balance. Specifically, the grounding line retreats (a along the B–B' flow line from ~ 40 to ~ 30 km (the distance from the summit, (b along the C–C' flow line from ~ 43 to ~ 37 km, and (c along the D–D' flow line from ~ 41 to ~ 32 km considering a time period of 500 years and assuming time-independent surface mass balance. Ice flow velocities in the ice streams decrease with time and this trend results in the overall decline of the outgoing ice flux. Generally, the modeled histories are in agreement with observations of sea ice extent and thickness indicating a continual ice decline in the Arctic.

  8. Flow and transport processes in a macroporous subsurface-drained glacial till soil

    Villholth, Karen Grothe; Jensen, Karsten Høgh; Fredericia, Johnny


    The qualitative and quantitative effects of macropore flow and transport in an agricultural subsurface-drained glacial till soil in eastern Denmark have been investigated. Three controlled tracer experiments on individual field plots (each approximately 1000 m(2)) were carried out by surface...... was evidenced directly by the rapid (within 10 mm of water input) and abrupt chloride breakthrough in the drainage water at 1.2 m depth in two of the tracer experiments. In the third experiment, the effect of macropore transport was obvious from the rapid and relatively deep penetration of the tracer...... into the soil profile. Dye infiltration experiments in the field as well as in the laboratory supported the recognition of the dominant contribution of macropores to the infiltration and transport process. The soil matrix significantly influenced the tracer distribution by acting as a source or sink...

  9. Sediment Mobilization and Storage Dynamics of a Debris Flow Impacted Stream Channel using Multi-Temporal Structure from Motion Photogrammetry

    Bailey, T. L.; Sutherland-Montoya, D.


    High resolution topographic analysis methods have become important tools in geomorphology. Structure from Motion photogrammetry offers a compelling vehicle for geomorphic change detection in fluvial environments. This process can produce arbitrarily high resolution, geographically registered spectral and topographic coverages from a collection of overlapping digital imagery from consumer cameras. Cuneo Creek has had three historically observed episodes of rapid aggradation (1955, 1964, and 1997). The debris flow deposits continue to be major sources of sediment sixty years after the initial slope failure. Previous studies have monitored the sediment storage volume and particle size since 1976 (in 1976, 1982, 1983, 1985, 1986, 1987, 1998, 2003). We reoccupied 3 previously surveyed stream cross sections on Sept 30, 2014 and March 30, 2015, and produced photogrammetric point clouds using a pole mounted camera with a remote view finder to take nadir view images from 4.3 meters above the channel bed. Ground control points were registered using survey grade GPS and typical cross sections used over 100 images to build the structure model. This process simultaneously collects channel geometry and we used it to also generate surface texture metrics, and produced DEMs with point cloud densities above 5000 points / m2. In the period between the surveys, a five year recurrence interval discharge of 20 m3/s scoured the channel. Surface particle size distribution has been determined for each observation period using image segmentation algorithms based on spectral distance and compactness. Topographic differencing between the point clouds shows substantial channel bed mobilization and reorganization. The net decline in sediment storage is in excess of 4 x 10^5 cubic meters since the 1964 aggradation peak, with associated coarsening of surface particle sizes. These new methods